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bbbb Basic in 180 Days Book V - Editor: Ramon F. aeroramon.com Contents

1 Day 1 1 1.1 Camera ...... 1 1.1.1 Functional description ...... 2 1.1.2 History ...... 2 1.1.3 Mechanics ...... 5 1.1.4 Formats ...... 8 1.1.5 Camera accessories ...... 8 1.1.6 Camera design history ...... 8 1.1.7 Image gallery ...... 12 1.1.8 See also ...... 14 1.1.9 References ...... 15 1.1.10 Bibliography ...... 16 1.1.11 External links ...... 17

2 Day 2 18 2.1 ...... 18 2.1.1 Physical explanation ...... 19 2.1.2 Technology ...... 19 2.1.3 History ...... 20 2.1.4 Role in the modern age ...... 31 2.1.5 Examples ...... 32 2.1.6 Public access ...... 33 2.1.7 See also ...... 33 2.1.8 Notes ...... 34 2.1.9 References ...... 34 2.1.10 Sources ...... 36

3 Day 3 39 3.1 ...... 39 3.1.1 History ...... 39 3.1.2 Usage ...... 39 3.1.3 Characteristics of pinhole camera photography ...... 40 3.1.4 Construction ...... 40

i ii CONTENTS

3.1.5 Selection of pinhole size ...... 41 3.1.6 Calculating the f-number & required ...... 42 3.1.7 Coded ...... 44 3.1.8 World Pinhole Day ...... 44 3.1.9 See also ...... 44 3.1.10 References ...... 44 3.1.11 External links ...... 45 3.1.12 Further reading ...... 45

4 Day 4 46 4.1 Single- reflex camera ...... 46 4.1.1 History ...... 47 4.1.2 Optical components ...... 52 4.1.3 mechanisms ...... 53 4.1.4 Further developments ...... 55 4.1.5 Film formats ...... 56 4.1.6 Common features ...... 57 4.1.7 Advantages ...... 57 4.1.8 Disadvantages ...... 58 4.1.9 Future of SLRs ...... 60 4.1.10 See also ...... 60 4.1.11 References ...... 60 4.1.12 Further reading ...... 60 4.1.13 External links ...... 60

5 Day 5 61 5.1 Mirrorless interchangeable-lens camera ...... 61 5.1.1 New technologies in mirrorless ...... 63 5.1.2 Market ...... 65 5.1.3 History ...... 66 5.1.4 Systems comparison ...... 68 5.1.5 References ...... 68

6 Day 6 70 6.1 Twin-lens reflex camera ...... 70 6.1.1 History ...... 70 6.1.2 Features ...... 70 6.1.3 Advantages ...... 71 6.1.4 Disadvantages ...... 72 6.1.5 Film formats ...... 72 6.1.6 Notes ...... 73 6.1.7 External links ...... 73 CONTENTS iii

7 Day 7 82 7.1 ...... 82 7.1.1 CCD vs CMOS technology ...... 82 7.1.2 Performance ...... 83 7.1.3 separation ...... 83 7.1.4 Specialty sensors ...... 84 7.1.5 Sensors used in digital cameras ...... 86 7.1.6 Companies ...... 86 7.1.7 See also ...... 87 7.1.8 References ...... 88 7.1.9 External links ...... 88 7.2 ...... 88 7.2.1 Sensor size and depth of field ...... 88 7.2.2 Sensor size, noise and ...... 90 7.2.3 Sensor size and diffraction ...... 91 7.2.4 Sensor format and lens size ...... 92 7.2.5 Active area of the sensor ...... 92 7.2.6 Sensor size and shading effects ...... 92 7.2.7 Common image sensor formats ...... 93 7.2.8 See also ...... 97 7.2.9 Notes and references ...... 97 7.2.10 External links ...... 99

8 Day 8 100 8.1 Full-frame digital SLR ...... 100 8.1.1 Use of 35mm film-camera ...... 100 8.1.2 Advantages and disadvantages of full-frame digital SLRs ...... 100 8.1.3 Past and present full-frame digital cameras ...... 102 8.1.4 Features of some full frame DSLR cameras ...... 104 8.1.5 Prototype full-frame digital SLRs ...... 105 8.1.6 See also ...... 105 8.1.7 References ...... 105

9 Day 9 107 9.1 Digital single-lens reflex camera ...... 107 9.1.1 Design of DSLR cameras ...... 107 9.1.2 Features commonly seen in DSLR designs ...... 108 9.1.3 History ...... 115 9.1.4 DSLRs compared to other digital cameras ...... 120 9.1.5 See also ...... 122 9.1.6 References ...... 122 9.1.7 External links ...... 124 iv CONTENTS

9.2 CMOS ...... 124 9.2.1 Technical details ...... 124 9.2.2 Inversion ...... 125 9.2.3 Power: switching and leakage ...... 128 9.2.4 Analog CMOS ...... 129 9.2.5 Temperature range ...... 129 9.2.6 Single- CMOS ...... 129 9.2.7 See also ...... 129 9.2.8 References ...... 130 9.2.9 Further reading ...... 130 9.2.10 External links ...... 130 9.3 Active sensor ...... 135 9.3.1 History ...... 135 9.3.2 Comparison to CCDs ...... 136 9.3.3 Architecture ...... 137 9.3.4 Design variants ...... 139 9.3.5 See also ...... 141 9.3.6 References ...... 141 9.3.7 Further reading ...... 142 9.3.8 External links ...... 142 9.4 Charge-coupled device ...... 142 9.4.1 History ...... 142 9.4.2 Basics of operation ...... 144 9.4.3 Detailed physics of operation ...... 145 9.4.4 Architecture ...... 146 9.4.5 Use in astronomy ...... 152 9.4.6 Color cameras ...... 154 9.4.7 Blooming ...... 156 9.4.8 See also ...... 156 9.4.9 References ...... 157 9.4.10 External links ...... 158 9.5 Shutter (photography) ...... 158 9.5.1 Camera shutter ...... 159 9.5.2 Shutter lag ...... 162 9.5.3 Shutter cycle ...... 162 9.5.4 Projector shutter ...... 162 9.5.5 See also ...... 162 9.5.6 References ...... 162 9.6 ...... 168 9.6.1 Location of the dial ...... 168 9.6.2 Modes ...... 168 CONTENTS v

9.6.3 See also ...... 170 9.6.4 References ...... 171 9.7 modes ...... 171 9.7.1 Manual-enabled modes ...... 171 9.7.2 Automatic modes ...... 173 9.7.3 Secondary modes ...... 174 9.7.4 See also ...... 175 9.7.5 References ...... 175 9.8 Shutter priority ...... 176 9.8.1 See also ...... 176 9.8.2 References ...... 176 9.9 priority ...... 177 9.9.1 Uses ...... 177 9.9.2 See also ...... 178 9.9.3 References ...... 178 9.10 Sensitivity priority ...... 178 9.10.1 See also ...... 178

10 Day 10 179 10.1 Bayer filter ...... 179 10.1.1 Explanation ...... 180 10.1.2 Demosaicing ...... 180 10.1.3 Artifacts ...... 181 10.1.4 Modifications ...... 181 10.1.5 See also ...... 182 10.1.6 References ...... 182 10.1.7 Notes ...... 182 10.1.8 External links ...... 183 10.2 Color filter array ...... 190 10.2.1 List of color filter arrays ...... 190 10.2.2 RGBW sensor ...... 190 10.2.3 CYGM sensor ...... 191 10.2.4 Manufacture of the CFA ...... 191 10.2.5 References ...... 192 10.2.6 See also ...... 193

11 Text and image sources, contributors, and licenses 194 11.1 Text ...... 194 11.2 Images ...... 200 11.3 Content license ...... 207 Chapter 1

Day 1

1.1 Camera

This article is about any optical photography instrument. For modern specifics, see digital camera. For other uses, see Camera (disambiguation). A camera is an optical instrument for recording or capturing images, which may be stored locally, transmitted to

A 1966 Canon FT camera with a 135mm 1:3.5 lens another location, or both. The images may be individual still or sequences of images constituting or movies. The camera is a remote sensing device as it senses subjects without physical contact. The word camera comes from camera obscura, which means “dark chamber” and is the Latin name of the original device for projecting an image of external reality onto a flat surface. The modern photographic camera evolved from the camera obscura. The functioning of the camera is very similar to the functioning of the human eye.

1 2 CHAPTER 1. DAY 1

1.1.1 Functional description

Viewfinder

Data display Lens Elements Shutter release

Electronic sensor

Aperture

Basic elements of a modern still camera

A camera may work with the of the visible spectrum or with other portions of the electromagnetic spectrum.[1] A still camera is an optical device which creates a single image of an object or scene and records it on an electronic sensor or photographic film. All cameras use the same basic design: light enters an enclosed box through a converging lens/convex lens and an image is recorded on a light-sensitive medium(mainly a transition metal-halide). A shutter mechanism controls the length of time that light can enter the camera.[2] Most photographic cameras have functions that allow a person to view the scene to be recorded, allow for a desired part of the scene to be in focus, and to control the exposure so that it is not too bright or too dim.[3] A display, often a liquid crystal display (LCD), permits the user to view scene to be recorded and settings such as ISO speed, exposure, and .[4][5] A or a camera operates similarly to a still camera, except it records a series of static images in rapid succession, commonly at a rate of 24 frames per second. When the images are combined and displayed in order, the illusion of motion is achieved.[6]

1.1.2 History

Main article:

The forerunner to the photographic camera was the camera obscura. Camera obscura (Arab for “Cabin”) is the natural optical phenomenon that occurs when an image of a scene at the other side of a screen (or for instance a wall) is projected through a small hole in that screen and forms an inverted image (left to right and upside down) on a surface opposite to the opening. The oldest known record of this principle is a description by Han Chinese philosopher Mozi (ca. 470 to ca. 391 BC). Mozi correctly asserted that the camera obscura image is inverted because light travels in straight lines from its source. In the 11th century Arab physicist Ibn al-Haytham (Alhazen)'s wrote very influential essays about experiments with light through a small opening in a darkened room. The use of a lens in the opening of a wall or closed window shutter of a darkened room to project images used as a drawing aid has been traced back to circa 1550. Since the late 17th century portable camera obscura devices in tents and boxes were used as a drawing aid. 1.1. CAMERA 3

Further information: Camera obscura

Before the development of the photographic camera, it had been known for hundreds of years that some substances, such as silver salts, darkened when exposed to sunlight.[7] In a series of experiments, published in 1727, the German scientist Johann Heinrich Schulze demonstrated that the darkening of the salts was due to light alone, and not influ- enced by heat or exposure to air.[8] The Swedish chemist Carl Wilhelm Scheele showed in 1777 that silver chloride was especially susceptible to darkening from light exposure, and that once darkened, it becomes insoluble in an am- monia solution.[8] The first person to use this chemistry to create images was Thomas Wedgwood.[7] To create images, Wedgwood placed items, such as leaves and insect wings, on ceramic pots coated with silver nitrate, and exposed the set-up to light. These images weren't permanent, however, as Wedgwood didn't employ a fixing mechanism. He ultimately failed at his goal of using the process to create fixed images created by a camera obscura.[9]

• Camera obscura. Light enters a dark box through a small hole and creates an inverted image on the wall opposite the hole.[10]

• View from the Window at Le Gras (1826), the earliest surviving [11]

• The Giroux camera, the first to be commercially produced[12]

The first permanent photograph of a camera image was made in 1826 by Joseph Nicéphore Niépce using a sliding wooden made by Charles and Vincent Chevalier in .[13] Niépce had been experimenting with ways to fix the images of a camera obscura since 1816. The photograph Niépce succeeded in creating shows the view from his window. It was made using an 8-hour exposure on pewter coated with bitumen.[14] Niépce called his process “”.[15] Niépce corresponded with the inventor Louis-Jacques-Mande Daguerre, and the pair entered into a partnership to improve the heliographic process. Niépce had experimented further with other chemicals, to improve contrast in his heliographs. Daguerre contributed an improved camera obscura design, but the partnership ended when Niépce died in 1833.[16] Daguerre succeeded in developing a high-contrast and extremely sharp image by exposing on a plate coated with silver iodide, and exposing this plate again to mercury vapor.[17] By 1837, he was able to fix 4 CHAPTER 1. DAY 1 the images with a common salt solution. He called this process Daguerreotype, and tried unsuccessfully for a couple years to commercialize it. Eventually, with help of the scientist and politician François Arago, the French government acquired Daguerre’s process for public release. In exchange, pensions were provided to Daguerre as well as Niépce’s son, Isidore.[18] In the 1830s, the English scientist independently invented a process to fix camera images using silver salts.[19] Although dismayed that Daguerre had beaten him to the announcement of photography, on January 31, 1839 he submitted a pamphlet to the Royal Institution entitled Some Account of the Art of Photogenic Drawing, which was the first published description of photography. Within two years, Talbot developed a two-step process for creating photographs on paper, which he called . The calotyping process was the first to utilize prints, which reverse all values in the photograph - black shows up as white and vice versa.[20] Negative prints allow, in principle, unlimited duplicates of the positive print to be made.[21] Calotyping also introduced the ability for a printmaker to alter the resulting image through retouching.[22] Calotypes were never as popular or widespread as ,[23] owing mainly to the fact that the latter produced sharper details.[24] However, because daguerreotypes only produce a direct positive print, no duplicates can be made. It is the two-step negative/positive process that formed the basis for modern photography.[25] The first photographic camera developed for commercial manufacture was a daguerreotype camera, built by Alphonse Giroux in 1839. Giroux signed a contract with Daguerre and Isidore Niépce to produce the cameras in ,[26] with each device and accessories costing 400 francs.[27] The camera was a double-box design, with a landscape lens fitted to the outer box, and a holder for a ground glass focusing screen and image plate on the inner box. By sliding the inner box, objects at various distances could be brought to as sharp a focus as desired. After a satisfactory image had been focused on the screen, the screen was replaced with a sensitized plate. A knurled wheel controlled a flap in front of the lens, which functioned as a shutter. The early daguerreotype cameras required long exposure times, which in 1839 could be from 5 to 30 minutes.[26][28] After the introduction of the Giroux daguerreotype camera, other manufacturers quickly produced improved varia- tions. Charles Chevalier, who had earlier provided Niépce with lenses, created in 1841 a double-box camera using a half-sized plate for imaging. Chevalier’s camera had a hinged bed, allowing for half of the bed to fold onto the back of the nested box. In addition to having increased portability, the camera had a faster lens, bringing exposure times down to 3 minutes, and a prism at the front of the lens, which allowed the image to be laterally correct.[29] Another French design emerged in 1841, created by Marc Antoine Gaudin. The Nouvel Appareil Gaudin camera had a metal disc with three differently-sized holes mounted on the front of the lens. Rotating to a different hole effectively pro- vided variable f-stops, letting in different amount of light into the camera.[30] Instead of using nested boxes to focus, the Gaudin camera used nested brass tubes.[31] In , Peter Friedrich Voigtländer designed an all-metal camera with a conical shape that produced circular pictures of about 3 inches in diameter. The distinguishing characteristic of the Voigtländer camera was its use of a lens designed by Josef Max Petzval.[32] The f/3.5 Petzval lens was nearly 30 times faster than any other lens of the period, and was the first to be made specifically for portraiture. Its design was the most widely used for portraits until Carl Zeiss introduced the anastigmat lens in 1889.[33] Within a decade of being introduced in America, 3 general forms of camera were in popular use: the American- or chamfered-box camera, the Robert’s-type camera or “Boston box”, and the Lewis-type camera. The American-box camera had beveled edges at the front and rear, and an opening in the rear where the formed image could be viewed on ground glass. The top of the camera had hinged doors for placing photographic plates. Inside there was one available slot for distant objects, and another slot in the back for close-ups. The lens was focused either by sliding or with a rack and pinion mechanism. The Robert’s-type cameras were similar to the American-box, except for having a knob-fronted worm gear on the front of the camera, which moved the back box for focusing. Many Robert’s-type cameras allowed focusing directly on the . The third popular daguerreotype camera in America was the Lewis-type, introduced in 1851, which utilized a bellows for focusing. The main body of the Lewis-type camera was mounted on the front box, but the rear section was slotted into the bed for easy sliding. Once focused, a set screw was tightened to hold the rear section in place.[34] Having the bellows in the middle of the body facilitated making a second, in-camera copy of the original image.[35] Daguerreotype cameras formed images on silvered copper plates. The earliest daguerreotype cameras required several minutes to half an hour to expose images on the plates. By 1840, exposure times were reduced to just a few seconds owing to improvements in the chemical preparation and development processes, and to advances in lens design.[36] American daguerreotypists introduced manufactured plates in mass production, and plate sizes became internationally standardized: whole plate (6.5 x 8.5 inches), three-quarter plate (5.5 x 7 1/8 inches), half plate (4.5 x 5.5 inches), quarter plate (3.25 x 4.25 inches), sixth plate (2.75 x 3.25 inches), and ninth plate (2 x 2.5 inches).[37] Plates were often cut to fit cases and jewelry with circular and oval shapes. Larger plates were produced, with sizes such as 9 x 13 inches (“double-whole” plate), or 13.5 x 16.5 inches (Southworth & Hawes’ plate).[38] 1.1. CAMERA 5

The collodion wet plate process that gradually replaced the daguerreotype during the 1850s required photographers to coat and sensitize thin glass or iron plates shortly before use and expose them in the camera while still wet. Early wet plate cameras were very simple and little different from Daguerreotype cameras, but more sophisticated designs eventually appeared. The Dubroni of 1864 allowed the sensitizing and developing of the plates to be carried out inside the camera itself rather than in a separate . Other cameras were fitted with multiple lenses for photographing several small portraits on a single larger plate, useful when making cartes de visite. It was during the wet plate era that the use of bellows for focusing became widespread, making the bulkier and less easily adjusted nested box design obsolete. For many years, exposure times were long enough that the photographer simply removed the lens cap, counted off the number of seconds (or minutes) estimated to be required by the lighting conditions, then replaced the cap. As more sensitive photographic materials became available, cameras began to incorporate mechanical shutter mechanisms that allowed very short and accurately timed exposures to be made. The use of photographic film was pioneered by , who started paper film in 1885 before switching to celluloid in 1889. His first camera, which he called the ",” was first offered for sale in 1888. It was a very simple box camera with a fixed-focus lens and single shutter speed, which along with its relatively low price appealed to the average consumer. The Kodak came pre-loaded with enough film for 100 exposures and needed to be sent back to the factory for processing and reloading when the roll was finished. By the end of the 19th century Eastman had expanded his lineup to several models including both box and folding cameras. Films also made possible capture of motion () establishing the movie industry by end of 19th century. The first camera using digital to capture and store images was developed by Kodak engineer in 1975. He used a charge-coupled device (CCD) provided by Fairchild , which provided only 0.01 megapixels to capture images. Sasson combined the CCD device with movie camera parts to create a digital camera that saved images onto a cassette tape.[39] The images were then read from the cassette and viewed on a TV monitor.[40] Later, cassette tapes were replaced by flash memory. Gradually in the 2000s and 2010s, digital cameras became the dominant type of camera across consumer, and movies.

1.1.3 Mechanics

Image capture

Traditional cameras capture light onto or photographic film. Video and digital cameras use an electronic image sensor, usually a charge coupled device (CCD) or a CMOS sensor to capture images which can be transferred or stored in a or other storage inside the camera for later playback or processing. Cameras that capture many images in sequence are known as movie cameras or as ciné cameras in Europe; those designed for single images are still cameras. However these categories overlap as still cameras are often used to capture moving images in special effects work and many modern cameras can quickly between still and motion recording modes.

Lens

Main articles: and

The lens of a camera captures the light from the subject and brings it to a focus on the sensor. The design and manufacture of the lens is critical to the quality of the photograph being taken. The technological revolution in camera design in the 19th century revolutionized optical glass manufacture and lens design with great benefits for modern lens manufacture in a wide range of optical instruments from reading to microscopes. Pioneers included Zeiss and Leitz. Camera lenses are made in a wide range of focal lengths. They range from extreme wide angle, and standard, medium telephoto. Each lens is best suited to a certain type of photography. The extreme wide angle may be preferred for architecture because it has the capacity to capture a wide view of a building. The normal lens, because it often has a wide aperture, is often used for street and . The is useful for sports and wildlife but it is more susceptible to camera shake.[41] 6 CHAPTER 1. DAY 1

Focus

The distance range in which objects appear clear and sharp, called depth of field, can be adjusted by many cameras. This allows for a photographer to control which objects appear in focus, and which do not.

Due to the optical properties of photographic lenses, only objects within a limited range of distances from the camera will be reproduced clearly. The process of adjusting this range is known as changing the camera’s focus. There are various ways of focusing a camera accurately. The simplest cameras have fixed focus and use a small aperture and wide-angle lens to ensure that everything within a certain range of distance from the lens, usually around 3 metres (10 ft) to infinity, is in reasonable focus. Fixed focus cameras are usually inexpensive types, such as single-use cameras. The camera can also have a limited focusing range or scale-focus that is indicated on the camera body. The user will guess or calculate the distance to the subject and adjust the focus accordingly. On some cameras this is indicated by symbols (head-and-shoulders; two people standing upright; one tree; mountains). Rangefinder cameras allow the distance to objects to be measured by means of a coupled parallax unit on top of the camera, allowing the focus to be set with accuracy. Single-lens reflex cameras allow the photographer to determine the focus and composition visually using the objective lens and a moving mirror to project the image onto a ground glass or plastic micro-prism screen. Twin-lens reflex cameras use an objective lens and a focusing lens unit (usually identical to the objective lens.) in a parallel body for composition and focusing. View cameras use a ground glass screen which is removed and replaced by either a photographic plate or a reusable holder containing sheet film before exposure. Modern cameras often offer systems to focus the camera automatically by a variety of methods.[42] Some experimental cameras, for example the planar Fourier capture array (PFCA), do not require focusing to allow them to take pictures. In conventional , lenses or mirrors map all of the light originating from a single point of an in-focus object to a single point at the sensor plane. Each pixel thus relates an independent piece of information about the far-away scene. In contrast, a PFCA does not have a lens or mirror, but each pixel has an idiosyncratic pair of diffraction gratings above it, allowing each pixel to likewise relate an independent piece of information (specifically, one component of the 2D Fourier transform) about the far-away scene. Together, complete scene information is captured and images can be reconstructed by computation. Some cameras have post focusing. Post focusing means take the pictures first and then focusing later at the personal . The camera uses many tiny lenses on the sensor to capture light from every camera angle of a scene and 1.1. CAMERA 7 is called plenoptics technology. A current plenoptic camera design has 40,000 lenses working together to grab the optimal picture.[43]

Exposure control

The size of the aperture and the brightness of the scene controls the amount of light that enters the camera during a period of time, and the shutter controls the length of time that the light hits the recording surface. Equivalent exposures can be made using a large aperture size with a fast shutter speed and a small aperture with a slow shutter.

Shutters

Main article: Shutter (photography)

Although a range of different shutter devices have been used during the development of the camera only two types have been widely used and remain in use today. The Leaf shutter or more precisely the in-lens shutter is a shutter contained within the lens structure, often close to the diaphragm consisting of a number of metal leaves which are maintained under spring tension and which are opened and then closed when the shutter is released. The exposure time is determined by the interval between opening and closing. In this shutter design, the whole film frame is exposed at one time. This makes flash synchronisation much simpler as the flash only needs to fire once the shutter is fully open. Disadvantages of such shutters are their inability to reliably produce very fast shutter speeds ( faster than 1/500th second or so) and the additional cost and weight of having to include a shutter mechanism for every lens. The focal-plane shutter operates as close to the film plane as possible and consists of cloth curtains that are pulled across the film plane with a carefully determined gap between the two curtains (typically running horizontally) or consisting of a series of metal plates (typically moving vertically) just in front of the film plane. The focal-plane shutter is primarily associated with the single lens reflex type of cameras, since covering the film rather than blocking light passing through the lens allows the photographer to view through the lens at all times except during the exposure itself. Covering the film also facilitates removing the lens from a loaded camera (many SLRs have interchangeable lenses).

Complexities Professional SLR (single-lens-reflex) cameras (typically using 120/220 roll film) use a hybrid solution, since such a large focal-plane shutter would be difficult to make and/or may run slowly. A manually inserted blade known as a dark slide allows the film to be covered when changing lenses or film backs. A blind inside the camera covers the film prior to and after the exposure (but is not designed to be able to give accurately controlled exposure times) and a leaf shutter that is normally open is installed in the lens. To take a picture, the leaf shutter closes, the blind opens, the leaf shutter opens then closes again, and finally the blind closes and the leaf shutter re-opens (the last step may only occur when the shutter is re-cocked). Using a focal-plane shutter, exposing the whole film plane can take much longer than the exposure time. The exposure time does not depend on the time taken to make the exposure over all, only on the difference between the time a specific point on the film is uncovered and then covered up again. For example, an exposure of 1/1000 second may be achieved by the shutter curtains moving across the film plane in 1/50th of a second but with the two curtains only separated by 1/20th of the frame width. In fact in practice the curtains do not run at a constant speed as they would in an ideal design, obtaining an even exposure time depends mainly on being able to make the two curtains accelerate in a similar manner. When photographing rapidly moving objects, the use of a focal-plane shutter can produce some unexpected effects, since the film closest to the start position of the curtains is exposed earlier than the film closest to the end position. Typically this can result in a moving object leaving a slanting image. The direction of the slant depends on the direction the shutter curtains run in (noting also that as in all cameras the image is inverted and reversed by the lens, i.e. “top-left” is at the bottom right of the sensor as seen by a photographer behind the camera). Focal-plane shutters are also difficult to synchronise with flash bulbs and electronic flash and it is often only possible to use flash at shutter speeds where the curtain that opens to reveal the film completes its run and the film is fully uncovered, before the second curtain starts to travel and cover it up again. Typically 35mm film SLRs could sync flash at only up to 1/60th second if the camera has horizontal run cloth curtains, and 1/125th if using a vertical run metal shutter. 8 CHAPTER 1. DAY 1

1.1.4 Formats

Main article: Film formats

A wide range of film and plate formats have been used by cameras. In the early history plate sizes were often specific for the make and model of camera although there quickly developed some standardisation for the more popular cameras. The introduction of roll film drove the standardization process still further so that by the 1950s only a few standard roll films were in use. These included 120 film providing 8, 12 or 16 exposures, 220 film providing 16 or 24 exposures, 127 film providing 8 or 12 exposures (principally in cameras) and 135 (35 mm film) providing 12, 20 or 36 exposures – or up to 72 exposures in the half-frame format or in bulk cassettes for the range. For cine cameras, film 35 mm wide and perforated with sprocket holes was established as the standard format in the 1890s. It was used for nearly all film-based professional motion picture production. For amateur use, several smaller and therefore less expensive formats were introduced. 17.5 mm film, created by splitting 35 mm film, was one early amateur format, but 9.5 mm film, introduced in Europe in 1922, and 16 mm film, introduced in the US in 1923, soon became the standards for “home movies” in their respective hemispheres. In 1932, the even more economical 8 mm format was created by doubling the number of perforations in 16 mm film, then splitting it, usually after exposure and processing. The Super 8 format, still 8 mm wide but with smaller perforations to make room for substantially larger film frames, was introduced in 1965.

1.1.5 Camera accessories

Accessories for cameras are mainly for care, protection, special effects and functions.

• : used on the end of a lens to block the sun or other light source to prevent glare and lens flare (see also matte box).

• Lens cap: covers and protects the lens during storage.

• Lens adapter: sometimes called a step-ring, adapts the lens to other size filters.

• Lens filters: allow artificial or change light density.

• Lens extension tubes allow close focus in .

• equipment: including light diffuser, mount and stand, reflector, soft box, trigger and cord.

• Care and protection: including camera case and cover, maintenance tools, and screen protector.

• cameras use special equipment which includes magnifier loupe, view finder, angle finder, focusing rail /truck.

• Battery and sometimes a charger.

• Some professional SLR could be provided with interchangeable finders for eye-level or waist-level focusing, focusing screens, eye-cup, data backs, motor-drives for film transportation or external battery packs.

• , microscope adapter, cable release, electric release.

1.1.6 Camera design history

Plate camera

Main article: Photographic plate

The earliest cameras produced in significant numbers used sensitised glass plates were plate cameras. Light entered a lens mounted on a which was separated from the plate by an extendible bellows.There were simple box cameras for glass plates but also single-lens reflex cameras with interchangeable lenses and even for 1.1. CAMERA 9

(Autochrome Lumière). Many of these cameras had controls to raise or lower the lens and to it forwards or backwards to control perspective. Focussing of these plate cameras was by the use of a ground glass screen at the point of focus. Because lens design only allowed rather small aperture lenses, the image on the ground glass screen was faint and most photographers had a dark cloth to cover their heads to allow focussing and composition to be carried out more easily. When focus and composition were satisfactory, the ground glass screen was removed and a sensitised plate put in its place protected by a dark slide. To make the exposure, the dark slide was carefully slid out and the shutter opened and then closed and the dark slide replaced. Glass plates were later replaced by sheet film in a dark slide for sheet film; adaptor sleeves were made to allow sheet film to be used in plate holders. In addition to the ground glass, a simple optical viewfinder was often fitted. Cameras which take single exposures on sheet film and are functionally identical to plate cameras were used for static, high-image-quality work; much longer in 20th century, see Large-format camera, below.

Folding camera

Main article: Folding camera

The introduction of films enabled the existing designs for plate cameras to be made much smaller and for the base- plate to be hinged so that it could be folded up compressing the bellows. These designs were very compact and small models were dubbed vest pocket cameras. Folding rollfilm cameras were preceded by folding plate cameras, more compact than other designs.

Box camera

Main article: Box camera

Box cameras were introduced as a budget level camera and had few if any controls. The original box Brownie models had a small reflex viewfinder mounted on the top of the camera and had no aperture or focusing controls and just a simple shutter. Later models such as the Brownie 127 had larger direct view optical viewfinders together with a curved film path to reduce the impact of deficiencies in the lens.

Rangefinder camera

Main article: Rangefinder camera

As camera a lens technology developed and wide aperture lenses became more common, rangefinder cameras were introduced to make focusing more precise. Early rangefinders had two separate viewfinder windows, one of which is linked to the focusing mechanisms and moved right or left as the focusing ring is turned. The two separate images are brought together on a ground glass viewing screen. When vertical lines in the object being photographed meet exactly in the combined image, the object is in focus. A normal composition viewfinder is also provided. Later the viewfinder and rangefinder were combined. Many rangefinder cameras had interchangeable lenses, each lens requiring its own range- and viewfinder linkages. Rangefinder cameras were produced in half- and full-frame 35 mm and rollfilm (medium format).

Instant picture camera

Main article:

After exposure every photograph is taken through pinch rollers inside of the instant camera. Thereby the developer paste contained in the paper 'sandwich' distributes on the image. After a minute, the cover sheet just needs to be removed and one gets a single original positive image with a fixed format. With some systems it was also possible to create an instant image negative, from which then could be made copies in the photo lab. The ultimate development was the SX-70 system of , in which a row of ten shots - engine driven - could be made without having to 10 CHAPTER 1. DAY 1 remove any cover sheets from the picture. There were instant cameras for a variety of formats, as well as cartridges with instant film for normal system cameras.

Single-lens reflex

Main article: Single-lens reflex camera

In the single-lens reflex camera, the photographer sees the scene through the camera lens. This avoids the problem of parallax which occurs when the viewfinder or viewing lens is separated from the taking lens. Single-lens reflex cameras have been made in several formats including sheet film 5x7” and 4x5”, roll film 220/120 taking 8,10, 12 or 16 photographs on a 120 roll and twice that number of a 220 film. These correspond to 6x9, 6x7, 6x6 and 6x4.5 respectively (all dimensions in cm). Notable manufacturers of large format and roll film SLR cameras include , Graflex, , Mamiya, and . However the most common format of SLR cameras has been 35 mm and subsequently the migration to digital SLR cameras, using almost identical sized bodies and sometimes using the same lens systems. Almost all SLR cameras use a front surfaced mirror in the optical path to direct the light from the lens via a viewing screen and pentaprism to the eyepiece. At the time of exposure the mirror is flipped up out of the light path before the shutter opens. Some early cameras experimented with other methods of providing through-the-lens viewing, including the use of a semi-transparent pellicle as in the Canon Pellix[44] and others with a small periscope such as in the Corfield Periflex series.[45]

Twin-lens reflex

Main article: Twin-lens reflex camera

Twin-lens reflex cameras used a pair of nearly identical lenses, one to form the image and one as a viewfinder. The lenses were arranged with the viewing lens immediately above the taking lens. The viewing lens projects an image onto a viewing screen which can be seen from above. Some manufacturers such as Mamiya also provided a reflex head to attach to the viewing screen to allow the camera to be held to the eye when in use. The advantage of a TLR was that it could be easily focussed using the viewing screen and that under most circumstances the view seen in the viewing screen was identical to that recorded on film. At close distances however, parallax errors were encountered and some cameras also included an indicator to show what part of the composition would be excluded. Some TLR had interchangeable lenses but as these had to be paired lenses they were relatively heavy and did not provide the range of focal lengths that the SLR could support. Most TLRs used 120 or 220 film; some used the smaller 127 film.

Large-format camera

Main article:

The large-format camera, taking sheet film, is a direct successor of the early plate cameras and remained in use for high quality photography and for technical, architectural and industrial photography. There are three common types, the view camera with its monorail and field camera variants, and the . They have an extensible bellows with the lens and shutter mounted on a lens plate at the front. Backs taking rollfilm, and later digital backs are available in addition to the standard dark slide back. These cameras have a wide range of movements allowing very close control of focus and perspective. Composition and focusing is done on view cameras by viewing a ground-glass screen which is replaced by the film to make the exposure; they are suitable for static subjects only, and are slow to use.

Medium-format camera

Main article: Medium-format 1.1. CAMERA 11

Medium-format cameras have a film size between the large-format cameras and smaller 35mm cameras. Typically these systems use 120 or 220 rollfilm. The most common image sizes are 6×4.5 cm, 6×6 cm and 6×7 cm; the older 6×9 cm is rarely used. The designs of this kind of camera show greater variation than their larger brethren, ranging from monorail systems through the classic Hasselblad model with separate backs, to smaller rangefinder cameras. There are even compact amateur cameras available in this format.

Subminiature camera

Main article: Subminiature camera

Cameras taking film significantly smaller than 35 mm were made. Subminiature cameras were first produced in the nineteenth century. The expensive 8×11 mm Minox, the only type of camera produced by the company from 1937 to 1976, became very widely known and was often used for espionage (the Minox company later also produced larger cameras). Later inexpensive subminiatures were made for general use, some using rewound 16 mm cine film. Image quality with these small film sizes was limited.

Movie camera

Main article: Movie camera

A ciné camera or movie camera takes a rapid sequence of photographs on image sensor or strips of film. In contrast to a still camera, which captures a single at a time, the ciné camera takes a series of images, each called a “frame” through the use of an intermittent mechanism. The frames are later played back in a ciné projector at a specific speed, called the "frame rate" (number of frames per second). While viewing, a person’s eyes and brain merge the separate pictures to create the illusion of motion. The first ciné camera was built around 1888 and by 1890 several types were being manufactured. The standard film size for ciné cameras was quickly established as 35mm film and this remained in use until transition to digital cinematography. Other professional standard formats include 70 mm film and 16mm film whilst amateurs film makers used 9.5 mm film, 8mm film or Standard 8 and Super 8 before the move into digital format. The size and complexity of ciné cameras varies greatly depending on the uses required of the camera. Some profes- sional equipment is very large and too heavy to be hand held whilst some amateur cameras were designed to be very small and light for single-handed operation.

Camcorders

Main article:

A is an electronic device combining a and a video recorder. Although marketing materials may use the colloquial term “camcorder”, the name on the package and manual is often “video camera recorder”. Most devices capable of recording video are camera phones and digital cameras primarily intended for still pictures; the term “camcorder” is used to describe a portable, self-contained device, with video capture and recording its primary function.

Professional video camera

Main article: Professional video camera

A professional video camera (often called a television camera even though the use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on film). Originally developed for use in television studios, they are now also used for music videos, direct-to-video movies, corporate and educational videos, marriage videos etc. These cameras earlier used vacuum tubes and later electronic sensors. 12 CHAPTER 1. DAY 1

Digital camera

Main article: Digital camera

A digital camera (or digicam) is a camera that encodes digital images and videos digitally and stores them for later reproduction.[46] Most cameras sold today are digital,[47] and digital cameras are incorporated into many devices ranging from mobile phones (called camera phones) to vehicles. Digital and film cameras share an optical system, typically using a lens with a variable diaphragm to focus light onto an image pickup device.[48] The diaphragm and shutter admit the correct amount of light to the imager, just as with film but the image pickup device is electronic rather than chemical. However, unlike film cameras, digital cameras can display images on a screen immediately after being recorded, and store and delete images from memory. Most digital cameras can also record moving videos with sound. Some digital cameras can crop and stitch pictures and perform other elementary image editing. Consumers adopted digital cameras in 1990s. Professional video cameras transitioned to digital around the 2000s- 2010s. Finally movie cameras transitioned to digital in the 2010s.

panoramic camera

Main article:

Panoramic cameras are fixed-lens digital action cameras. They usually have a single fish-eye lens or multiple lenses, to cover the entire 180° up to 360° in their field of view.

VR Camera Main article: VR photography

VR cameras are panoramic cameras that also cover the top and bottom in their field of view. . There have also been camera rigs employing multiple cameras to cover the whole 360° by 360° field of view. The most famous VR camera rig is known as 'Google Jump'.

1.1.7 Image gallery

• The Giroux daguerreotype camera, the first to be commercially produced[12]

• 19th century studio camera, with bellows for focusing 1.1. CAMERA 13

• Rangefinder camera, Leica c. 1936

• with a Summicron-M 28/2 ASPH Lens

• Olympus Four Thirds single-lens reflex camera

• Twin-lens reflex camera

• Cinématographe Lumière at the Institut Lumière, France 14 CHAPTER 1. DAY 1

• Front and back of Canon PowerShot A95, a typical pocket-size digital camera

• Digital television camera by

• Arri Alexa, a digital movie camera

•

Zenit-E with Helios 44-2 lens

1.1.8 See also

• List of camera types

• Photography

• Cinematography

• Cameras in mobile phones

• Camera Obscura 1.1. CAMERA 15

1.1.9 References

[1] Gustavson, pg. VII

[2] Young, Freedman & Ford, pg. 1182-1183

[3] London, Upton, Kobré & Brill, pg. 4

[4] London, Upton, Kobré & Brill, pp. 6-7

[5] Burian & Caputo, pg. 12

[6] Ascher & Pincus, pg. 4

[7] Gustavson, pg. 4

[8] Gernsheim, pg. 7

[9] Gernsheim, pg. 8

[10] Kirkpatrick, Larry D.; Francis, Gregory E. (2007). “Light”. Physics: A World View (6 ed.). Belmont, California: Thomson Brooks/Cole. p. 339. ISBN 0-495-01088-X.

[11] Gustavson, pp. 3-5

[12] Gustavson, pg. 9

[13] Gernsheim, pp. 9-11

[14] Gernsheim, pg. 9

[15] Gustavson, pg. 5

[16] Gernsheim, pg. 10

[17] Gustavson, pg. 6

[18] Gernsheim, pg. 11

[19] Hirsch, pg. 15

[20] Gustavson, pg. 21

[21] Hirsch, pg. 16

[22] Hirsch, pg. 67

[23] Gustavson, pg. 22

[24] London, et. al., pg. 370

[25] Gernsheim, pg. 15

[26] Gustavson, pp. 8-9

[27] Frizot, pg. 38

[28] Frizot, pg. 39

[29] Gustavson (500 Cameras), pg. 6

[30] Spira, Lothrop, and Spira, pg. 28

[31] Gustavson (500 Cameras), pg. 7

[32] Hirsch, pg. 34

[33] Gernsheim, pg. 19

[34] Spira, Lothrop, and Spira, pp. 26-27

[35] Gustavson (500 Cameras), pg. 17

[36] Starl, pg. 38 16 CHAPTER 1. DAY 1

[37] Hirsch, pp. 33-34 [38] Spira, pg. 25 [39] Gustavson (500 Cameras), pg. 442 [40] Hitchcock, pg. 225 [41] McHugh, Sean. “Understanding Camera Lenses”. Cambridge in Colour. Archived from the original on 2013-08-19. [42] Brown, Gary. “How Autofocus Cameras Work”. HowStuffWorks.com. Archived from the original on 2013-09-30. [43] Wehner, Mike (2011-10-19). “Lytro camera lets you focus after shooting, now available for pre-order”. Yahoo! News. Archived from the original on 2011-10-22. [44] “Canon Pellix Camera”. Photography in Malaysia. Archived from the original on 2013-10-16. [45] Parker, Bev. “Corfield Cameras - The Periflex Era”. Wolverhampton Museum of Industry. [46] Farlex Inc: definition of digital camera at the Free Dictionary; retrieved 2013-09-07 [47] Musgrove, Mike (2006-01-12). “ Says It’s Leaving Film-Camera Business”. Washington Post. Retrieved 2007-02- 23. [48] MakeUseOf: How does a Digital Camera Work; retrieved 2013-09-07

1.1.10 Bibliography

• Ascher, Steven; Pincus, Edward (2007). The Filmmaker’s Handbook: A Comprehensive Guide for the Digital Age (3 ed.). New York, New York: Penguin Group. ISBN 978-0-452-28678-8. • Burian, Peter; Caputo, Robert (2003). Geographic photography field guide (2 ed.). Washington, D.C.: National Geographic Society. ISBN 0-7922-5676-X. • Frizot, Michel. “Light machines: On the threshold of invention”. In Michel Frizot. A New History of Photog- raphy. Koln, Germany: Konemann. ISBN 3-8290-1328-0. • Gernsheim, Helmut (1986). A Concise (3 ed.). Mineola, New York: Dover Publica- tions, Inc. ISBN 0-486-25128-4. • Gustavson, Todd (2009). Camera: a history of photography from daguerreotype to digital. New York, New York: Sterling Publishing Co., Inc. ISBN 978-1-4027-5656-6. • Gustavson, Todd (1 Nov 2011). 500 Cameras: 170 Years of Photographic Innovation. Toronto, Ontario: Sterling Publishing, Inc. ISBN 978-1-4027-8086-8. • Hirsch, Robert (2000). Seizing the Light: A History of Photography. New York, New York: McGraw-Hill Companies, Inc. ISBN 0-697-14361-9. • Hitchcock, Susan (editor) (20 Sep 2011). Susan Tyler Hitchcock, eds. National Geographic complete photog- raphy. Washington, D.C.: National Geographic Society. ISBN 978-1-4351-3968-8. • Johnson, William S.; Rice, Mark; Williams, Carla (2005). Therese Mulligan and David Wooters, eds. A History of Photography. Los Angeles, California: Taschen America. ISBN 978-3-8228-4777-0. • London, Barbara; Upton, John; Kobré, Kenneth; Brill, Betsy (2002). Photography (7 ed.). Upper Saddle River, New Jersey: Prentice Hall. ISBN 0-13-028271-5. • Spira, S.F.; Lothrop, Jr., Easton S.; Spira, Jonathan B. (2001). The History of Photography as Seen Through the Spira Collection. New York, New York: Aperture. ISBN 978-0893819538. • Starl, Timm. “A New World of Pictures: The Daguerreotype”. In Michel Frizot. A New History of Photogra- phy. Koln, Germany: Konemann. ISBN 3-8290-1328-0. • Wenczel, Norma (2007). “Part I - Introducing an Instrument”. In Wolfgang Lefèvre. The Optical Camera Obscura II Images and Texts (PDF). Inside the Camera Obscura – and Art under the Spell of the Projected Image. Max Planck Institute for the History of Science. pp. 13–30. Archived from the original (PDF) on 2 April 2012. • Young, Hugh D.; Freedman, Roger A.; Ford, A. Lewis (2008). Sears and Zemansky’s University Physics (12 ed.). San Francisco, California: Pearson Addison-Wesley. ISBN 0-321-50147-0. 1.1. CAMERA 17

1.1.11 External links

• Camera at Encyclopædia Britannica • How camera works at How stuff works. Chapter 2

Day 2

2.1 Camera obscura

This article is about an optical device. For other uses, see Camera obscura (disambiguation). Camera obscura (from Latin “camera": (vaulted) chamber or room, and “obscura": darkened, plural: camerae

illustration of the camera obscura principle

obscurae), also referred to as pinhole image, is the natural optical phenomenon that occurs when an image of a scene at the other side of a screen (or for instance a wall) is projected through a small hole in that screen as a reversed and inverted image (left to right and upside down) on a surface opposite to the opening. The surroundings of the projected image have to be relatively dark for the image to be clear, so many historical camera obscura experiments were performed in dark rooms. The term “camera obscura” also refers to constructions or devices that make use of the principle within a box, tent or room. Camerae obscurae with a lens in the opening have been used since the second half of the 16th century and became popular as an aid for drawing and painting. The camera obscura box was developed further into the photographic camera in the first half of the 19th century when camera obscura boxes were used to expose light- sensitive materials to the projected image. Before the term “camera obscura” was first used in 1604, many other expressions were used including “cubiculum obscurum”, “cubiculum tenebricosum”, “conclave obscurum” and “locus obscurus”.[1] A camera obscura device without a lens but with a very small hole is sometimes referred to as a "pinhole camera", although this more often refers to simple (home-made) lens-less cameras in which photographic film or photographic

18 2.1. CAMERA OBSCURA 19

An image of the New Royal Palace at Prague Castle projected onto an attic wall by a hole in the tile roofing.

paper is used.

2.1.1 Physical explanation

Rays of light travel in straight lines and change when they are reflected and partly absorbed by an object, retaining information about the color and brightness of the surface of that object. Lit objects reflect rays of light in all directions. A small enough opening in a screen only lets through rays that travel directly from different points in the scene on the other side and together form an image of that scene when they are reflected on a surface into the eye of an observer. The human eye itself works much like a camera obscura with an opening (pupil), a biconvex lens and a surface where the image is formed ().

2.1.2 Technology

A camera obscura device consists of a box, tent or room with a small hole in one side. Light from an external scene passes through the hole and strikes a surface inside, where the scene is reproduced, inverted (thus upside-down) and reversed (left to right), but with color and perspective preserved. The image can be projected onto paper, and can then be traced to produce a highly accurate representation. In order to produce a reasonably clear projected image, the aperture has to be about 1/100th the distance to the screen, or less. Many camerae obscurae use a lens rather than a pinhole (as in a pinhole camera) because it allows a larger aperture, giving a usable brightness while maintaining focus. As the pinhole is made smaller, the image gets sharper, but the projected image becomes dimmer. With too small a pinhole, however, the sharpness worsens, due to diffraction. Using mirrors, as in an 18th-century overhead version, it is possible to project a right-side-up image. Another more portable type is a box with an angled mirror projecting onto tracing paper placed on the glass top, the image being upright (but still reversed) as viewed from the back. 20 CHAPTER 2. DAY 2

A diagram of a camera obscura with an upright projected image at the top.

2.1.3 History

30.000 BCE to 500 BCE: Possible inspiration for prehistoric art and possible use in religious ceremonies

There are theories that occurrences of camera obscura effects (through tiny holes in tents or in screens of animal hide) inspired paleolithic cave paintings. Distortions in the shapes of animals in many paleolithic cave artworks might be inspired by distortions seen when the surface on which an image was projected was not straight or not in the right angle.[2] It is also suggested that camera obscura projections could have played a role in Neolithic structures.[3][4] Some ancient sightings of gods and spirits, especially in temple worship, are thought to possibly have been conjured up by means of camera obscura projections.[5][6][7]

500 BCE to 500 CE: Earliest written observations

The earliest extant written record of the camera obscura is to be found in Chinese writings dated to the −4th century called Mozi, traditionally ascribed to and named for Mozi (circa 470 BCE-circa 391 BCE), a Han Chinese philosopher and the founder of Mohist School of Logic. In these writings it is explained how the inverted image in a “collecting- point” or “treasure house”[note 1] is inverted by an intersecting point (a pinhole) that collected the (rays of) light. Light coming from the foot of an illuminated person would partly be hidden below (strike below the pinhole) and partly form the top part of the image. Rays from the head would partly be hidden above (strike above the pinhole) and partly form the lower part of the image. This is a remarkably early correct description of the camera obscura; there are no other examples known that are dated before the 11th century.[7] The Greek philosopher Aristotle (384-322 BCE), or possibly a follower of his ideas, touched upon the subject in the work Problems - Book XV, asking:

“Why is it that when the sun passes through quadri-laterals, as for instance in wickerwork, it does not produce a figure rectangular in shape but circular?” 2.1. CAMERA OBSCURA 21

Holes in the leaf canopy project images of a solar eclipse on the ground. and further on:

“Why is it that an eclipse of the sun, if one looks at it through a sieve or through leaves, such as a plane-tree or other broadleaved tree, or if one joins the fingers of one hand over the fingers of the other, the rays are crescent-shaped where they reach the earth? Is it for the same reason as that when light shines through a rectangular peep-hole, it appears circular in the form of a cone?"

Aristotle never found an answer. The mystery was resolved centuries later, when it was concluded that the circular shapes on the ground were camera obscura projections of the sun and thus became crescent-shaped during an eclipse. Euclid is sometimes reported to have mentioned the camera obscura phenomenon as a demonstration that light travels in straight lines in his very influential Optics (circa 300 BCE).[8] However, in common translations[9] no remarks of anything that resembles camera obscura can be found. Claims could be based on later versions, since Ignazio Danti added a description of camera obscura in his 1573 annotated translation.[10] In the 4th century, Greek scholar Theon of Alexandria observed that “candlelight passing through a pinhole will create an illuminated spot on a screen that is directly in line with the aperture and the center of the candle.”

500 to 1100: Experiments, study of light

In the 6th century, the Byzantine-Greek mathematician and architect Anthemius of Tralles (most famous for designing the Hagia Sophia), used a type of camera obscura in his experiments.[11] In the 9th century, Al-Kindi (Alkindus) demonstrated that “light from the right side of the flame will pass through the aperture and end up on the left side of the screen, while light from the left side of the flame will pass through the aperture and end up on the right side of the screen.” In the 10th century Yu Chao-Lung supposedly projected images of pagoda models through a small hole onto a screen to study directions and divergence of rays of light.[12] 22 CHAPTER 2. DAY 2

Arab physicist Ibn al-Haytham (known in the West by the latinised Alhazen) (965–1039) explained in his Book of Optics (circa 1027) that rays of light travel in straight lines and are distinguished by the body that reflected the rays and then wrote:

“Evidence that light and color do not mingle in air or (other) transparent bodies is (found in) the fact that, when several candles are at various distinct locations in the same area, and when they all face a window that opens into a dark recess, and when there is a white wall or (other white) opaque body in the dark recess facing that window, the (individual) of those candles appear individually upon that body or wall according to the number of those candles; and each of those lights (spots of light) appears directly opposite one (particular) candle along a straight line passing through that window. Moreover, if one candle is shielded, only the light opposite that candle is extinguished, but if the shielding object is lifted, the light will return.”[13]:91#5:p379[6.85],[6.86]

ﻙ ﺭ ﺩ ﺏ ﺍ ﻫ ﺤ ﺡ ﻁ

A diagram depicting Al-Haytam’s observations of light’s behaviour through a pinhole he (مقالة في صورةالكسوف :In his 1038 essay “On the form of the Eclipse” (Maqalah-fi-Surat-al-Kosuf) (Arabic wrote:

“The image of the sun at the time of the eclipse, unless it is total, demonstrates that when its light passes through a narrow, round hole and is cast on a plane opposite to the hole it takes on the form of a moon-sickle. The image of the sun shows this peculiarity only when the hole is very small. When the hole is enlarged, the picture changes, and the change increases with the added width. When the aperture is very wide, the sickle-form image will disappear, and the light will appear round when the hole is round, square if the hole is square, and if the shape of the opening is irregular, the light on the wall will take on this shape, provided that the hole is wide and the plane on which it is thrown is parallel to it.”[14]

Al-Haytham also analyzed the rays of sunlight and concluded that they make a conic shape where they meet at the hole, forming another conic shape reverse to the first one from the hole to the opposite wall in the dark room (see illustration). Ibn al-Haytham is reported to have stated about the camera obscura: “We did not invent this”.[15] al- Haytam’s writings on optics became very influential in Europe through Latin translations since circa 1200. Among the people who he inspired were Witelo, John Peckham, , Leonardo Da Vinci, René Descartes and .[16] In his 1088 book Dream Pool Essays the Song Dynasty Chinese scientist Shen Kuo (1031–1095) compared the focal point of a concave burning-mirror and the “collecting” hole of camera obscura phenomena to an oar in a rowlock to explain how the images were inverted:

“When a bird flies in the air, its shadow moves along the ground in the same direction. But if its image is collected (shu)(like a belt being tightened) through a small hole in a window, then the shadow moves in the direction opposite of that of the bird.[...] This is the same principle as the burning-mirror. 2.1. CAMERA OBSCURA 23

Such a mirror has a concave surface, and reflects a finger to give an upright image if the object is very near, but if the finger moves farther and farther away it reaches a point where the image disappears and after that the image appears inverted. Thus the point where the image disappears is like the pinhole of the window. So also the oar is fixed at the rowlock somewhere at its middle part, constituting, when it is moved, a sort of 'waist' and the handle of the oar is always in the position inverse to the end (which is in the water).”

Shen Kuo also responded to a statement of Duan Chengshi in Miscellaneous Morsels from Youyang written in about 840 that the inverted image of a Chinese pagoda tower beside a seashore, was inverted because it was reflected by the sea: “This is nonsense. It is a normal principle that the image is inverted after passing through the small hole.”[7]

1100 to 1400: Optical and astronomical tool, entertainment

English statesman and scholastic philosopher Robert Grosseteste (c. 1175 – 9 October 1253) commented on the camera obscura.[17]

Three-tiered camera obscura, 13th century? (attributed to Roger Bacon)

English philosopher and Franciscan friar Roger Bacon (c. 1219/20 – c. 1292) tried to answer Aristotle’s question (see above), but falsely argued that light travels in spherical waves and therefore assumed its natural shape after passing through square holes. He also advised to study solar eclipses safely by observing the rays passing through some round hole and studying the spot of light they form on a surface.[18] Bacon wrote about optics in his work Opus Majus Part five De Scientia Perspectivae (1267) for which he seems to have studied the writings of Al-Kindi and Al-Haytam. Bacon is sometimes thought to have used a camera obscura projection in combination with mirrors, based on a passage in his book which says (translated from Latin):

“Mirrors may be so arranged that we may see whatever we choose and anything in the house or in the street, and everyone looking at those things will see them as if they were real, but when they go to the spot they will find nothing. For the mirrors can be hidden from things in such a way that the images will be in the open and will appear in the air at the intersection of the visual rays and the catheti 24 CHAPTER 2. DAY 2

(perpendicular plane), and therefore those looking at them would run up to the places where they appear and would judge that the objects are there when there is in reality nothing except an image.”

Others point out this contains no evidence of camera obscura and think this possibly alludes to projection with concave mirrors.[19] A picture of a three-tiered camera obscura (see illustration) is attributed to Bacon, but its origins are not further defined.[20] A very similar picture illustrates pages 129 and 130 of the 1646 edition of Athanasius Kircher’s Ars Magna Lucis et Umbrae.[21] Polish friar, theologian, physicist, mathematician and natural philosopher Erazmus Ciołek Witelo (also known as Vitello Thuringopolonis and by many different spellings of the name “Witelo”) wrote about the camera obscura in his very influential treatise Perspectiva (circa 1270-1278), which was largely based on Ibn al-Haytham’s work. English archbishop and scholar John Peckham (circa 1230 – 1292) wrote about the camera obscura in his Tractatus de Perspectiva (circa 1269-1277) and Perspectiva communis (circa 1277-79), falsely arguing that light gradually forms the circular shape after passing through the aperture.[22] His writings were influenced by Roger Bacon. At the end of the 13th century, Arnaldus de Villa Nova is credited with using a camera obscura to project live performances for entertainment.[23][24] French astronomer Guillaume de Saint-Cloud suggested in his 1292 work Almanach Planetarum that the eccentricity of the sun could be determined with the camera obscura from the inverse proportion between the distances and the apparent solar diameters at apogee and perigee.[25] Kamāl al-Dīn al-Fārisī (1267–1319) described in his 1309 work Kitab Tanqih al-Manazir (The Revision of the Optics) how he experimented with a glass sphere filled with water in a camera obscura with a controlled aperture and found that the colors of the rainbow are phenomena of the decomposition of light.[26][27] French Jewish philosopher, mathematician, physicist and astronomer/astrologer Levi ben Gershon (1288–1344) (also known as Gersonides or Leo de Balneolis) made several astronomical observations using a camera obscura with a Jacob’s staff, describing methods to measure the angular diameters of the sun, the moon and the bright planets Venus and . He determined the eccentricity of the sun based on his observations of the summer and winter solstices in 1334. Levi also noted how the size of the aperture determined the size of the projected image. He wrote about his findings in Hebrew in his treatise Sefer Milhamot Ha-Shem (The Wars of the Lord) Book V Chapters 5 and 9.[28]

1450 to 1600: Gnomon, earliest depiction, lenses, drawing aid, mirrors

Italian astronomer, mathematician and cosmographer Paolo Toscanelli is associated with the 1475 placement of a bronze plate with a round hole in the dome of the Cathedral of Santa Maria del Fiore in Florence to project an image of the sun on the cathedral’s floor. With markings on the floor it functions as a gnomon that tells the exact time of each midday (reportedly to within half a second) as well as the date of the summer solstice. Italian mathematician, engineer, astronomer and geographer Leonardo Ximenes reconstructed the gnomon according to his new measurements in 1756.[29] Italian polymath Leonardo da Vinci (1452–1519), familiar with the work of Alhazen in Latin translation and after an extensive study of optics and human vision, wrote the oldest known clear description of the camera obscura in mirror writing in a in 1502, later published in the collection Codex Atlanticus (translated from Latin):

If the facade of a building, or a place, or a landscape is illuminated by the sun and a small hole is drilled in the wall of a room in a building facing this, which is not directly lighted by the sun, then all objects illuminated by the sun will send their images through this aperture and will appear, upside down, on the wall facing the hole. You will catch these pictures on a piece of white paper, which placed vertically in the room not far from that opening, and you will see all the above-mentioned objects on this paper in their natural shapes or colors, but they will appear smaller and upside down, on account of crossing of the rays at that aperture. If these pictures originate from a place which is illuminated by the sun, they will appear colored on the paper exactly as they are. The paper should be very thin and must be viewed from the back.[31]

These descriptions, however, would remain unknown until Venturi deciphered and published them in 1797.[32] Da Vinci also drew 270 diagrams of the camera obscura in his .[33] 2.1. CAMERA OBSCURA 25

The gnomon projection on the floor of the Santa Maria del Fiore Cathedral during the solstice on 21.06.2012

The camera obscura’s potential as a drawing aid may have been familiar to artists by as early as the 15th century. The oldest known published drawing of a camera obscura is found in Dutch physician, mathematician and instrument maker Gemma Frisius’ 1545 book De Radio Astronomica et Geometrica, in which he described and illustrated how he used the camera obscura to study the solar eclipse of January 24, 1544[32] Italian polymath Gerolamo Cardano described using a biconvex lens in a camera obscura in his 1550 book De sub- tilitate, vol. I, Libri I-VII,[34] Sicilian mathematician and astronomer Francesco Maurolico (1494-1575) answered Aristotle’s problem how sunlight that shines through rectangular holes can form round spots of light or crescent-shaped spots during an eclipse in his treatise Photismi de lumine et umbra (1521-1554). However this wasn't published before 1611,[35] after Johannes Kepler had published similar findings of his own. Italian polymath Giambattista della Porta described the camera obscura, which he called “obscurum cubiculum”, in the 1558 first edition of his book series Magia Naturalis. He suggested to use a convex mirror to project the image onto paper and to use this as a drawing aid. Della Porta compared the human eye to the camera obscura: “For the image is let into the eye through the eyeball just as here through the window”. The popularity of Della Porta’s books helped spread knowledge of the camera obscura.[36][37] In his 1567 work La Pratica della Perspettiva Venetian nobleman Daniello Barbaro (1513-1570) described using a camera obscura with a biconvex lens as a drawing aid.[34] In his influential and meticulously annotated Latin edition of the works of Al-Haytam and Witelo Opticae thesauru (1572) German mathematician Friedrich Risner proposed a portable camera obscura drawing aid; a lightweight wooden hut with lenses in each of its four walls that would project images of the surroundings on a paper cube in the middle. The construction could be carried on two wooden poles.[38] A very similar setup was illustrated in 1645 in Athanasius Kircher's influential book Ars Magna Lucis Et Umbrae.[39] Around 1575 Italian Dominican priest, mathematician, astronomer, and cosmographer Ignazio Danti designed a camera obscura gnomom and a meridian line for the Basilica of Santa Maria Novella, Florence and he later had a massive gnomon built in the San Petronio church in Bologna. The gnomon was used to study the movements of 26 CHAPTER 2. DAY 2

Da Vinci: Let a b c d e be the object illuminated by the sun and o r the front of the dark chamber in which is the said hole at n m. Let s t be the sheet of paper intercepting the rays of the images of these objects upside down, because the rays being straight, a on the right hand becomes k on the left, and e on the left becomes f on the right[30] the sun during the year and helped in determining the new Gregorian calendar for which Danti took place in the commission appointed by Pope Gregorius XIII and instituted in 1582.[40] In his 1585 book Diversarum Speculationum Mathematicarum[41] Venetian mathematician Giambattista Benedetti proposed to use a mirror in a 45 degree angle to project the image upright. This leaves the image reversed, but would become common practice in later camera obscura boxes.[34] Giambattista della Porta added a “lenticular crystal” or biconvex lens to the camera obscura description in the 1589 second edition of Magia Naturalis. He also imagined use of the camera obscura to project hunting scenes, battles, games or anything desired. Real or artificial forests, rivers, mountains as well as animals could be used for scenes on an outside stage and projected into a dark room with spectators.[36][42][43]

1600 to 1650: Name coined, camera obscura telescopy, portable drawing aid in tents and boxes

The oldest use of the term “camera obscura” is found in the 1604 book Ad Vitellionem Paralipomena by German mathematician, astronomer, and astrologer Johannes Kepler.[44] Kepler discovered the working of the camera obscura by recreating its principle with a book replacing a shining body and sending threads from its edges through a many- cornered aperture in a table onto the floor where the threads recreated the shape of the book. He also realized that images are “painted” inverted and reversed on the retina of the eye and figured that this is somehow corrected by the brain.[45] In 1607 Kepler studied the sun in his camera obscura and noticed a sunspot, but he thought it was Mercury 2.1. CAMERA OBSCURA 27

First published picture of camera obscura in Gemma Frisius’ 1545 book De Radio Astronomica et Geometrica

Illustration of “portable” camera obscura (similar to Risner’s proposal) in Kircher’s Ars Magna Lucis Et Umbrae (1645) transiting the sun.[46] In his 1611 book Dioptrice Kepler described how the projected image of the camera obscura can be improved and reverted with a lens. It is believed he later used a telescope with three lenses to revert the image in the camera obscura.[34] In 1611 Frisian/German astronomers David and Johannes Fabricius (father and son) studied sunspots with a camera obscura, after realizing looking at the sun directly with the telescope could damage their eyes.[46] They are thought to have combined the telescope and the camera obscura into camera obscura telescopy. In 1612 Italian mathematician Benedetto Castelli wrote to his mentor, the Italian astronomer, physicist, engineer, philosopher and mathematician Galilei about projecting images of the sun through a telescope (invented in 1608) to study the recently discovered sunspots. Galilei wrote about Castelli’s technique to the German Jesuit priest, physicist and astronomer Christoph Scheiner.[47] From 1612 to at least 1630 Christoph Scheiner would keep on studying sunspots and constructing new telescopic solar 28 CHAPTER 2. DAY 2

Detail of Scheiner’s Oculus hoc est (1619) frontispiece with a camera obscura’s projected image reverted by a lens. projection systems. He called these “Heliotropii Telioscopici”, later contracted to helioscope.[47] For his helioscope studies Scheiner built a box around the viewing/projecting end of the telescope, which can be seen as the oldest known version of a box-type camera obscura. Scheiner also made a portable camera obscura.[48] In his 1613 book Opticorum Libri Sex[49] Belgian Jesuit mathematician, physicist and architect François d'Aguilon described how some charlatans cheated people out of their money by claiming they knew necromancy and would raise the specters of the devil from hell to show them to the audience inside a dark room. The image of an assistant with a devil’s mask was projected through a lens into the dark room, scaring the uneducated spectators.[18] By 1620 Kepler used a portable camera obscura tent with a modified telescope to draw landscapes. It could be turned around to capture the surroundings in parts.[50] Dutch inventor Cornelis Drebbel is thought to have constructed a box-type camera obscura which corrected the inversion of the projected image. In 1622 he sold one to the Dutch poet, composer and diplomat Constantijn Huygens who used it to paint and recommended it to his artist friends.[38] Huygens wrote to his parents (translated from French):

I have at home Drebbel’s other instrument, which certainly makes admirable effects in painting from reflection in a dark room; it is not possible for me to reveal the beauty to you in words; all painting is dead by comparison, for here is life itself or something more elevated if one could articulate it. The figure and the contour and the movements come together naturally therein and in a grandly pleasing fashion.[51]

German Orientalist, mathematician, inventor, poet, and librarian Daniel Schwenter wrote in his 1636 book Deliciae Physico-Mathematicae about an instrument that a man from Pappenheim had shown him, which enabled movement 2.1. CAMERA OBSCURA 29

Scheiner’s helioscope as illustrated in his book Rosa Ursina sive Sol (1626-30)

A camera obscura drawing aid tent in an illustration for an 1858 book on physics of a lens to project more from a scene through the camera obscura. It consisted of a ball as big as a fist, through which a hole (AB) was made with a lens attached on one side (B). This ball was placed inside two halves of part of a hollow ball that were then glued together (CD), in which it could be turned around. This device was attached to a wall of the camera obscura (EF).[52] This universal joint mechanism was later called a scioptric ball. In his 1637 book Dioptrique French philosopher, mathematician and scientist René Descartes suggested placing an 30 CHAPTER 2. DAY 2

Illustration of a scioptic ball with a lens from Daniel Schwenter’s Deliciae Physico-Mathematicae (1636)

eye of a recently dead man (or if a dead man was unavailable, the eye of an ox) into an opening in a darkened room and scraping away the flesh at the back until one could see the inverted image formed on the retina.[53] Italian Jesuit philosopher, mathematician and astronomer Mario Bettini wrote about making a camera obscura with twelve holes in his Apiaria universae philosophiae mathematicae (1642). When a foot soldier would stand in front of the camera, a twelve person army of soldiers making the same movements would be projected. French mathematician, Minim friar, and painter of anamorphic art Jean-François Nicéron (1613-1646) wrote about the camera obscura with convex lenses. He explained how the camera obscura could be used by painters to achieve perfect perspective in their work. He also complained how charlatans abused the camera obscura to fool witless spectators and make them believe that the projections were magic or occult science. These writings were published in a posthumous version of La Perspective Curieuse (1652).[54]

1650 to 1800: Introduction of the magic lantern, popular portable box-type drawing aid, painting aid

German Jesuit scientist Gaspar Schott heard from a traveler about a small camera obscura device he had seen in Spain, which one could carry under one arm and could be hidden under a coat. He then constructed his own sliding box camera obscura, which could focus by sliding a wooden box part fitted inside another wooden box part. He wrote about this in his 1657 Magia universalis naturæ et artis (volume 1 - book 4 “Magia Optica” pages 199-201). By 1659 the magic lantern was introduced and partly replaced the camera obscura as a projection device, while the camera obscura mostly remained popular as a drawing aid. The magic lantern can be seen as a development of the (box-type) camera obscura device. 2.1. CAMERA OBSCURA 31

Illustration of a twelve hole camera obscura from Bettini’s Apiaria universae philosophiae mathematicae” (1642)

The 17th century Dutch Masters, such as Johannes Vermeer, were known for their magnificent attention to detail. It has been widely speculated that they made use of camerae obscurae, but the extent of their use by artists at this period remains a matter of considerable controversy, recently revived by the Hockney–Falco thesis.[38] German philosopher Johann Sturm published an illustrated article about the construction of a portable camera obscura box with a 45° mirror and an oiled paper screen in his book Collegium experimentale: sive curiosum (1676).[55] Johann Zahn's Oculus Artificialis Teledioptricus Sive Telescopium, published in 1685, contains many descriptions, diagrams, illustrations and sketches of both the camera obscura and the magic lantern. A hand-held device with a mirror reflex mechanism was first proposed by Johann Zahn in 1685, a design that would later be used in photographic cameras.[56] The scientist Robert Hooke presented a paper in 1694 to the Royal Society, in which he described a portable camera obscura. It was a cone-shaped box which fit onto the head and shoulders of its user.[57] From the beginning of the 18th century craftsmen and opticians would make camera obscura devices in the shape of books, which were much appreciated by lovers of optical devices.[18] One chapter in the Conte Algarotti’s Saggio sopra Pittura (1764) is dedicated to the use of a camera ottica (“optic chamber”) in painting.[58] By the 18th century, following developments by Robert Boyle and Robert Hooke, more easily portable models in boxes became available. These were extensively used by amateur artists while on their travels, but they were also employed by professionals, including Paul Sandby, Canaletto and Joshua Reynolds, whose camera (disguised as a book) is now in the Science Museum in London. Such cameras were later adapted by Joseph Nicephore Niepce, and William Fox Talbot for creating the first photographs.

2.1.4 Role in the modern age

While the technical principles of the camera obscura have been known since antiquity, the broad use of the technical concept in producing images with a linear perspective in paintings, maps, theatre setups and architectural and later photographic images and movies started in the Western Renaissance and the scientific revolution. While e.g. Alhazen (Ibn al-Haytham) had already observed an optical effect and developed a state of the art theory of the refraction of light, he was less interested to produce images with it (compare Hans Belting 2005); the society he lived in was even 32 CHAPTER 2. DAY 2

Illustration of a portable camera obscura device from Johann Sturm’s Collegium experimentale, sive curiosum (1676)

hostile (compare Aniconism in Islam) towards personal images.[59] Western artists and philosophers used the Arab findings in new frameworks of epistemic relevance.[60] E.g. Leonardo da Vinci used the camera obscura as a model of the eye, René Descartes for eye and mind and John Locke started to use the camera obscura as a metaphor of human understanding per se.[61] The modern use of the camera obscura as an epistemic machine had important side effects for science.[62][63]

2.1.5 Examples

• A freestanding room-sized camera obscura at the University of North Carolina at Chapel Hill. A pinhole can be seen to the left of the door.

• A freestanding room-sized camera obscura in the shape of a camera. Cliff House, San Francisco 2.1. CAMERA OBSCURA 33

• Image of the South Downs of Sussex in the camera obscura of Foredown Tower, Portslade, England

• A camera obscura created by Mark Ellis in the style of an Adirondack mountain cabin, Lake Flower, Saranac Lake, NY

• A 19th-century artist using a camera obscura to outline his subject

• A modern-day camera obscura

• A modern-day camera obscura used indoors

2.1.6 Public access

2.1.7 See also

• Addicted to Love - 1997 American film in which a camera obscura plays a prominent role

• Bonnington Pavilion - the first Scottish Camera Obscura dating from 1708

• Black mirror

• Bristol Observatory

• Camera

• Camera lucida

• History of cinema

• Hockney–Falco thesis 34 CHAPTER 2. DAY 2

• Magic lantern

• Optics

• Pepper’s ghost

2.1.8 Notes

[1] In the Mozi passage, a camera obscura is described as a “collecting-point” or “treasure house” (); the 18th century scholar Bi Yuan () suggested this was a misprint for “screen” ().

2.1.9 References

[1] Phelps Gage, Henry (1914). Optic projection, principles, installation, and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine.

[2] http://paleo-camera.com/paleolithic/

[3] http://paleo-camera.com/neolithic/

[4] http://gizmodo.com/did-prehistoric-people-watch-the-stars-through-this-6-0-1782759791

[5] http://paleo-camera.com/ancient-greece/

[6] Ruffles, Tom (2004). Ghost Images: Cinema of the Afterlife. pp. 15–17.

[7] Needham, Joseph. Science and Civilization in China, vol. IV, part 1: Physics and Physical Technology (PDF).

[8] Ben-Menahem. Historical Encyclopedia of Natural and Mathematical Sciences, Volume 1. p. 465.

[9] Optics of Euclid (PDF).

[10] “Kleine Geschichte der Lochkamera oder Camera Obscura” (in German).

[11] G. Huxley (1959) Anthemius of Tralles: a study of later Greek Geometry pp.6-8,pp.44-46 as cited in (Crombie 1990), p.205

[12] Hammond, John H. (1981). The camera obscura: a chronicle. p. 2.

[13] • Smith, A. Mark, ed. and trans. (2001) Alhacen’s Theory of visual perception : a critical edition, with English translation and commentary, of the first three books of Alhacen’s De aspectibus, [the medieval latin version of Ibn al-Haytham’s Kitāb al-Manāẓir], Transactions of the American Philosophical Society, 2 vols: 91(#4 — Vol 1 Com- mentary and Latin text); 91(#5 — Vol 2 English translation). (Philadelphia: American Philosophical Society), 2001. Books I-III (2001) Vol 1 Commentary and Latin text via JSTOR; Vol 2 English translation, Notes, Bibl. via JSTOR

[14] Eder, JOSEF MARIA (1945). HISTORY OF PHOTOGRAPHY. p. 37.

[15] Adventures in CyberSound: The Camera Obscura

[16] Plott, John C. (1984). Global History of Philosophy: The Period of scholasticism (part one). p. 460.

[17] A reconsideration of Roger Bacon’s theory of pinhole images

[18] Mannoni, Laurent (2000). The great art of light and shadow.

[19] http://www.theodora.com/encyclopedia/c/camera_obscura.html

[20] Doble, Rick (2012). 15 Years of Essay-Blogs About Contemporary Art & Digital Photography.

[21] Kircher, Athanasius (1646). Ars Magna Lucis et Umbrae.

[22] Lindberg, David C.; Pecham, John (1972). Tractatus de perspectiva.

[23] Burns, Paul T. “The History of the Discovery of Cinematography”. Archived from the original on 2013-12-31. Retrieved 2014-01-04.

[24] Smith, Roger. “A Look Into Camera Obscuras”. Retrieved 2014-10-23.

[25] Mancha, J.L. “Studies in Medieval Astronomy and Optics”. pp. 275–297. 2.1. CAMERA OBSCURA 35

[26] Nader El-Bizri, “Optics”, in Medieval Islamic Civilization: An Encyclopedia, ed. Josef W. Meri (New York – London: Routledge, 2005), Vol. II, pp. 578–580

[27] Nader El-Bizri, “Al-Farisi, Kamal al-Din,” in The Biographical Encyclopaedia of Islamic Philosophy, ed. Oliver Leaman (London — New York: Thoemmes Continuum, 2006), Vol. I, pp. 131–135

[28] Goldstein, Bernard R. The Astronomy of Levi ben Gerson. pp. 140–143.

[29] Suter, Rufus (1964). “Leonardo Ximenes and the Gnomon at the Cathedral of Florence”.

[30] “fromoldbooks.org - The Notebooks of Leonardo da Vinic”.

[31] Josef Maria Eder History of Photography translated by Edward Epstean Hon. F.R.P.S Copyright Columbia University Press

[32] Grepstad, Jon. “Pinhole Photography – History, Images, Cameras, Formulas”.

[33] http://www.sumscorp.com/leonardo_studies/news_98.html

[34] Ilardi, Vincent (2007). Renaissance Vision from Spectacles to Telescopes.

[35] Maurolico, Francesco (1611). Photismi de lumine et umbra.

[36] Larsen, Kenneth. “Sonnet 24”.

[37] Durbin, P.T. (2012). Philosophy of Technology. p. 74.

[38] Snyder, Laura J. (2015). “Eye of the Beholder”.

[39] Kircher, Athanasius (1645). “Ars Magna Lucis Et Umbrae” (in Latin). p. 806b.

[40] Cassini. “1655-2005: 350 Years of the Great Meridian Line”.

[41] Benedetti, Giambattista (1585). Diversarum Speculationum Mathematicarum (in Latin).

[42] http://idea.uwosh.edu/nick/dellaporta.pdf

[43] Zielinski, Siegfried (1996). “Media Archaeology”.

[44] Dupre, Sven (2008). “Inside the “Camera Obscura": Kepler’s Experiment and Theory of Optical Imagery”. Early Science and Medicin. 13 (3): 219–244. JSTOR 20617729.

[45] Lindberg, David C. (1981). Theories of Vision from Al-kindi to Kepler.

[46] “March 9, 1611: Dutch astronomer Johannes Fabricius observes sunspots”.

[47] Whitehouse, David (2004). “The Sun: A Biography”.

[48] Daxecker, Franz (2006). “Christoph Scheiner und die Camera obscura”.

[49] d'Aguilon, François (1613). Opticorum Libri Sex philosophis juxta ac mathematicis utiles.

[50] Steadman, Philip (2001). Vermeer’s camera.

[51] Wheelock, Jr, Arthur K. (2013). Constantijn huygens and early attitudes towards the camera obscura.

[52] Schwenter, Daniel (1636). Deliciae Physico-Mathematicae (in German). p. 255.

[53] Collins, Jane; Nisbet, Andrew (2012). Theatre and Performance Design: A Reader in Scenographyy.

[54] Nicéron, Jean François (1652). La Perspective curieuse (in French).

[55] Sturm, Johann (1676). Collegium experimentale, sive curiosum (in Latin). pp. 161–163.

[56] Gernsheim, pp. 5-6

[57] Wenczel, pg. 15

[58] Algarotti, Francesco (1764). Presso Marco Coltellini, Livorno, ed. Saggio sopra la pittura. pp. 59–63.

[59] Hans Belting Das echte Bild. Bildfragen als Glaubensfragen. München 2005, ISBN 3-406-53460-0

[60] An Anthropological Trompe L'Oeil for a Common World: An Essay on the Economy of Knowledge, Alberto Corsin Jimenez, Berghahn Books, 15.06.2013 36 CHAPTER 2. DAY 2

[61] Philosophy of Technology: Practical, Historical and Other Dimensions P.T. Durbin Springer Science & Business Media

[62] Contesting Visibility: Photographic Practices on the East African Coast Heike Behrend transcript, 2014

[63] Don Ihde Art Precedes Science: or Did the Camera Obscura Invent Modern Science? In Instruments in Art and Science: On the Architectonics of Cultural Boundaries in the 17th Century Helmar Schramm, Ludger Schwarte, Jan Lazardzig, Walter de Gruyter, 2008

2.1.10 Sources

• Crombie, Alistair Cameron (1990), Science, optics, and music in medieval and early modern thought, Contin- uum International Publishing Group, p. 205, ISBN 978-0-907628-79-8, retrieved 22 August 2010 • Kelley, David H.; Milone, E. F.; Aveni, A. F. (2005), Exploring Ancient Skies: An Encyclopedic Survey of Archaeoastronomy, Birkhäuser, ISBN 0-387-95310-8, OCLC 213887290 • Hill, Donald R. (1993), “Islamic Science and Engineering”, Edinburgh University Press, page 70.

• Lindberg, D.C. (1976), “Theories of Vision from Al Kindi to Kepler”, The University of Chicago Press, Chicago and London.

• Nazeef, Mustapha (1940), “Ibn Al-Haitham As a Naturalist Scientist”, (Arabic), published proceedings of the Memorial Gathering of Al-Hacan Ibn Al-Haitham, 21 December 1939, Egypt Printing.

• Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd. • Omar, S.B. (1977). “Ibn al-Haitham’s Optics”, Bibliotheca Islamica, Chicago.

• Wade, Nicholas J.; Finger, Stanley (2001), “The eye as an optical instrument: from camera obscura to Helmholtz’s perspective”, Perception, 30 (10): 1157–1177, doi:10.1068/p3210, PMID 11721819 2.1. CAMERA OBSCURA 37

Camera obscura in Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers. 18th century 38 CHAPTER 2. DAY 2

Four drawings by Canaletto, representing Campo San Giovanni e Paolo in Venice, obtained with a camera obscura (Venice, Gallerie dell'Accademia)

Cameras obscura for Daguerreotype called “Grand Photographe” produced by Charles Chevalier (Musée des Arts et Métiers). Chapter 3

Day 3

3.1 Pinhole camera

A pinhole camera is a simple camera without a lens but with a tiny aperture, a pinhole – effectively a light-proof box with a small hole in one side. Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box, which is known as the camera obscura effect.

3.1.1 History

Further information: Camera Obscura

Sometimes it is mistakenly claimed that for instance Alhazen (965–1039) or earlier philosophers already used pinhole cameras, while in most instances the “cameras” that were originally described were either natural occurrences of the camera obscura effect or experiments with darkened rooms (or chambers) with an opening much larger than a pinhole. The claims are mainly a result of many descriptions of the history of the camera lacking differentiation between the camera obscura effect, camera obscura rooms, camera obscura boxes (usually with a lens), or actual pinhole cameras. Most usage of the camera obscura before it was fitted with a lens in the 16th century can arguably be regarded as “hole cameras”. However, this would mainly concern rooms that were darkened (leaving a small opening in a shutter) to study the behavior of light or the projected image of the sun. The oldest known description of pinhole photography is found in the 1856 book The by Scottish inventor David Brewster, including the description of the idea as “a camera without lenses, and with only a pin-hole”. One older use of the term “pin-hole” in the context of optics was found in James Ferguson’s 1764 book Lectures on select subjects in mechanics, hydrostatics, pneumatics, and optics.[1] Sir William Crookes and William de Wiveleslie Abney were other early photographers to try the pinhole technique.[2]

3.1.2 Usage

The image of a pinhole camera may be projected onto a translucent screen for real-time viewing (used for safe observation of solar eclipses) or to trace the image on paper. But it is more often used without a translucent screen for pinhole photography with photographic film or photographic paper placed on the surface opposite to the pinhole aperture. A common use of pinhole photography is to capture the movement of the sun over a long period of time. This type of photography is called solargraphy. Pinhole photography is used for artistic reasons, but also for educational purposes to let pupils learn about, and experiment with, the basics of photography. Pinhole cameras with CCDs (charge coupled devices) are sometimes used for surveillance because they are difficult to detect. Related cameras, image forming devices, or developments from it include Franke’s widefield pinhole camera, the pinspeck camera, and the pinhead mirror.

39 40 CHAPTER 3. DAY 3

3.1.3 Characteristics of pinhole camera photography

• Pinhole photographs have nearly infinite depth of field, everything appears in focus. • As there’s no lens distortion, wide angle images remain absolutely rectilinear. • Exposure times are usually long, resulting in motion blur around moving objects and the absence of objects that moved too fast.

Other special features can be built into pinhole cameras such as the ability to take double images by using multiple pinholes, or the ability to take pictures in cylindrical or spherical perspective by curving the film plane.

3.1.4 Construction

A home-made pinhole camera (on the left), wrapped in black plastic to prevent light leaks, and related developing supplies

Pinhole cameras can be handmade by the photographer for a particular purpose. In its simplest form, the photographic pinhole camera can consist of a light-tight box with a pinhole in one end, and a piece of film or photographic paper wedged or taped into the other end. A flap of cardboard with a tape hinge can be used as a shutter. The pinhole may be punched or drilled using a sewing needle or small diameter bit through a piece of tinfoil or thin aluminum or brass sheet. This piece is then taped to the inside of the light-tight box behind a hole cut through the box. A cylindrical oatmeal container may be made into a pinhole camera. The interior of an effective pinhole camera is black to avoid any reflection of the entering light onto the photographic material or viewing screen.[3] Pinhole cameras can be constructed with a sliding film holder or back so the distance between the film and the pinhole can be adjusted. This allows the of the camera to be changed and also the effective f-stop ratio of the camera. Moving the film closer to the pinhole will result in a wide angle field of view and a shorter exposure time. Moving the film farther away from the pinhole will result in a telephoto or narrow angle view and a longer exposure time. Pinhole cameras can also be constructed by replacing the lens assembly in a conventional camera with a pinhole. In particular, compact 35 mm cameras whose lens and focusing assembly have been damaged can be reused as pinhole cameras—maintaining the use of the shutter and film winding mechanisms. As a result of the enormous increase in f-number while maintaining the same exposure time, one must use a fast film in direct sunshine. 3.1. PINHOLE CAMERA 41

Pinholes (homemade or commercial) can be used in place of the lens on an SLR. Use with a digital SLR allows metering and composition by trial and error, and is effectively free, so is a popular way to try pinhole photography.[4] Unusual materials have been used to construct pinhole cameras, e.g., a Chinese roast duck.[5] by Martin Cheung

3.1.5 Selection of pinhole size

Up to a certain point, the smaller the hole, the sharper the image, but the dimmer the projected image. Optimally, the size of the aperture should be 1/100 or less of the distance between it and the projected image. Within limits, a smaller pinhole (with a thinner surface that the hole goes through) will result in sharper because the projected at the image plane is practically the same size as the pinhole. An extremely small hole, however, can produce significant diffraction effects and a less clear image due to the wave properties of light.[6] Additionally, occurs as the diameter of the hole approaches the thickness of the material in which it is punched, because the sides of the hole obstruct the light entering at anything other than 90 degrees. The best pinhole is perfectly round (since irregularities cause higher-order diffraction effects), and in an extremely thin piece of material. Industrially produced pinholes benefit from laser etching, but a hobbyist can still produce pinholes of sufficiently high quality for photographic work. One method is to start with a sheet of brass shim or metal reclaimed from an aluminium drinks can or tin foil/aluminum foil, use fine sand paper to reduce the thickness of the centre of the material to the minimum, before carefully creating a pinhole with a suitably sized needle. A method of calculating the optimal pinhole diameter was first attempted by Jozef Petzval. The crispest image is obtained using a pinhole size determined by the formula[7]

√ d = 2 fλ where d is pinhole diameter, f is (distance from pinhole to image plane) and λ is the wavelength of light. For standard black-and-white film, a wavelength of light corresponding to - (550 nm) should yield opti- mum results. For a pinhole-to-film distance of 1 inch (25 mm), this works out to a pinhole 0.24 mm in diameter.[8] For 5 cm, the appropriate diameter is 0.33 mm.[9] The depth of field is basically infinite, but this does not mean that no optical blurring occurs. The infinite depth of field means that image blur depends not on object distance, but on other factors, such as the distance from the aperture to the film plane, the aperture size, and the wavelength(s) of the light source.

An example of a 20 minute exposure taken with a pinhole camera

A photograph taken with a pinhole camera using an exposure time of 2s 42 CHAPTER 3. DAY 3

In the 1970s, Young measured the resolution limit of the pinhole camera as a function of pinhole diameter[10] and

A graph of the resolution limit of the pinhole camera as a function of focal length (image distance). later published a tutorial in The Physics Teacher.[11] Partly to enable a variety of diameters and focal lengths, he defined two normalized variables: pinhole radius divided by resolution limit, and focal length divided by the quantity s2/λ, where s is the radius of the pinhole and λ is the wavelength of the light, typically about 550 nm. His results are plotted in the figure. To the left, the pinhole is large, and geometric optics applies; the resolution limit is about 1.5 times the radius of the pinhole. (Spurious resolution is also seen in the geometric-optics limit.) To the right, the pinhole is small, and Fraunhofer diffraction applies; the resolution limit is given by the far-field diffraction formula shown in the graph and now increases as the pinhole is made smaller. In the region of near-field diffraction (or Fresnel diffraction), the pinhole focuses the light slightly, and the resolution limit is minimized when the focal length f (the distance between the pinhole and the film plane) is given by f = s2/λ. At this focal length, the pinhole focuses the light slightly, and the resolution limit is about 2/3 of the radius of the pinhole. The pinhole in this case is equivalent to a Fresnel with a single zone. The value s2/λ is in a sense the natural focal length of the pinhole. The relation f = s2/λ yields an optimum pinhole diameter d = 2 √(fλ), so the experimental value differs slightly from the estimate of Petzval, above.

3.1.6 Calculating the f-number & required exposure

The f-number of the camera may be calculated by dividing the distance from the pinhole to the imaging plane (the focal length) by the diameter of the pinhole. For example, a camera with a 0.5 mm diameter pinhole, and a 50 mm focal length would have an f-number of 50/0.5, or 100 (f/100 in conventional notation). Due to the large f-number of a pinhole camera, exposures will often encounter reciprocity failure.[12] Once exposure time has exceeded about 1 second for film or 30 seconds for paper, one must compensate for the breakdown in linear response of the film/paper to intensity of illumination by using longer exposures. Exposures projected on to modern light-sensitive photographic film can typically range from five seconds up to as much as several hours, with smaller pinholes requiring longer exposures to produce the same size image. Because a pinhole camera requires a lengthy exposure, its shutter may be manually operated, as with a flap made of opaque material to cover and uncover the pinhole. 3.1. PINHOLE CAMERA 43

A fire hydrant photographed by a pinhole camera made from a shoe box, exposed on photographic paper (top). The length of the exposure was 40 seconds. There is noticeable flaring in the bottom-right corner of the image, likely due to extraneous light entering the camera box. 44 CHAPTER 3. DAY 3

3.1.7 Coded apertures

Main article: Coded aperture

A non-focusing coded-aperture optical system may be thought of as multiple pinhole cameras in conjunction. By adding pinholes, light throughout and thus sensitivity are increased. However, multiple images are formed, usually requiring computer deconvolution.

3.1.8 World Pinhole Day

World Pinhole Day is held on the last Sunday of April.[13]

3.1.9 See also

•

• Spatial filter

• Zone plate

• Dirkon

• Ibn al-Haytham

• Fox Talbot

• Wolf Howard

• Billy Childish

• Jesse Richards

• Pinhole camera model

• Nautilus (whose pinhole eye functions as a camera obscura)

• Pinhole occluder, a similar device used by ophthalmologists

• Camera obscura, uses the same principle as a pinhole camera

• The Great Picture

3.1.10 References

[1] http://idea.uwosh.edu/nick/oldarticles.htm

[2] Pinhole photography history

[3] {cite web|url=http://www.kodak.com/ek/US/en/Pinhole_Camera.htm%7Ctitle=How to Make and Use a Pinhole Camera}

[4] http://www.pcw.co.uk/personal-computer-world/features/2213298/hands-digital-pinhole-camera

[5] http://www.urbanphoto.net/blog/2010/11/25/how-a-roast-duck-sees-chinatown/

[6] Hecht, Eugene (1998). “5.7.6 The Camera”. Optics (3rd ed.). ISBN 0-201-30425-2.

[7] Rayleigh, (1891) Lord Rayleigh on Pin-hole Photography in Philosophical Magazine, vol.31, pp. 87–99 presents his formal analysis, but the layman’s formula “pinhole radius = √(ƒλ)" appears in Strutt,J.W. Lord Rayleigh (1891) Some applications of photography in Nature. Vol.44 p.254.

[8] Equation for calculation with f=1in, using Google for evaluation

[9] Equation for calculation with f=5cm, using Google for evaluation 3.1. PINHOLE CAMERA 45

[10] Young, M. (1971). “Pinhole optics”. Applied Optics. 10: 2763–2767. doi:10.1364/ao.10.002763.

[11] Young, Matt (1989). “The pinhole camera: Imaging without lenses or mirrors”. The Physics Teacher. 27: 648–655. doi:10.1119/1.2342908.

[12] http://www.nancybreslin.com/pinholetech.html

[13] http://pinholeday.org/org/

3.1.11 External links

• pinhole.cz

• Pinhole Photography by Vladimir Zivkovic • Worldwide Pinhole Photography Day website

• An easy way to convert a DSLR to a pinhole camera • Pinhole Photography and Camera Design Calculators

• Illustrated history of cinematography • How to Make and Use a Pinhole Camera

• Oregon Art Beat: Pinhole Photos by Zeb Andrews

3.1.12 Further reading

• Eric Renner Pinhole Photography: From Historic Technique to Digital Application Chapter 4

Day 4

4.1 Single-lens reflex camera

The historic Zeiss Ikon VEB S, manufactured in Dresden, one of the two original pentaprism SLRs for eye-level viewing that went into production in 1949. The Italian Rectaflex offered its first production SLR, the series 1000, the same year.

A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system (hence “reflex” from the mirror’s reflection) that permits the photographer to view through the lens and see exactly what will be captured. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image. When the shutter button is pressed on a mechanical SLR, the mirror flips out of the light path, allowing light to pass through to the light receptor, allowing the image to be captured.

46 4.1. SINGLE-LENS REFLEX CAMERA 47

4.1.1 History

Main article: History of the single-lens reflex camera

• Medium format SLR by Hasselblad (Model 1600F), Sweden

• Medium format SLR by Bronica (Model S2), Japan. Bronica’s later model—the Bron- ica EC—was the first medium format SLR camera to use an electrically operated focal-plane shutter

• The 1952 (Pentax) Asahiflex, Japan's first single-lens reflex camera.

• The Contaflex III a single-lens reflex camera from West Germany from 1957, with ad- ditional 115 mm lens

• The 35 mm film-based , 1959, the world’s second single-lens reflex system camera. The first was Kamera-Werke’s Praktica.

• Canon Pellix, 1965, the first camera to incorporate a stationary pellicle mirror. 48 CHAPTER 4. DAY 4

• The IIa, 1971

• Olympus The 35 mm film-based Olympus OM-2 (1975), which was the first SLR to measure light for electronic flash off the film plane.

• RF2 35mm film SLR

• Nikon F5 professional SLR, 1996

• Digital SLR and a Nikon film scanner

• Zenit, rare Russian brand. SLR without lens kit

Prior to the development of SLR, all cameras with viewfinders had two optical light paths: one path through the lens to the film, and another path positioned above (TLR or twin-lens reflex) or to the side (rangefinder). Because the viewfinder and the film lens cannot share the same optical path, the viewing lens is aimed to intersect with the film lens at a fixed point somewhere in front of the camera. This is not problematic for pictures taken at a middle or longer distance, but parallax causes errors in close-up shots. Moreover, focusing the lens of a fast reflex camera when it is opened to wider apertures (such as in low light or while using low-speed film) is not easy. Most SLR cameras permit upright and laterally correct viewing through use of a roof pentaprism situated in the optical path between the reflex mirror and viewfinder. Light, which comes both horizontally and vertically inverted 4.1. SINGLE-LENS REFLEX CAMERA 49 after passing through the lens, is reflected upwards by the reflex mirror, into the pentaprism where it is reflected several times to correct the inversions caused by the lens, and align the image with the viewfinder. When the shutter is released, the mirror moves out of the light path, and the light shines directly onto the film (or in the case of a DSLR, the CCD or CMOS imaging sensor). The Canon Pellix film camera was an exception to the moving mirror system, wherein the mirror was a fixed beamsplitting pellicle. Focus can be adjusted manually by the photographer or automatically by an autofocus system. The viewfinder can include a matte focusing screen located just above the mirror system to diffuse the light. This permits accurate viewing, composing and focusing, especially useful with interchangeable lenses. Up until the 1990s, SLR was the most advanced photographic preview system available, but the recent development and refinement of technology with an on-camera live LCD preview screen has overshadowed SLR’s popularity. Nearly all inexpensive compact digital cameras now include an LCD preview screen allowing the pho- tographer to see what the CCD is capturing. However, SLR is still popular in high-end and professional cameras because they are system cameras with interchangeable parts, allowing customization. They also have far less shutter lag, allowing photographs to be timed more precisely. Also the pixel resolution, contrast ratio, , and color gamut of an LCD preview screen cannot compete with the clarity and shadow detail of a direct-viewed optical SLR viewfinder. Large format SLR cameras were probably first marketed with the introduction of C.R. Smith’s Monocular Duplex (U.S., 1884).[1] SLRs for smaller exposure formats were launched in the 1920s by several camera makers. The first 35mm SLR available to the mass market, Leica’s PLOOT reflex housing along with a 200mm f4.5 lens paired to a 35mm rangefinder camera body, debuted in 1935. The Soviet Спорт (“Sport”),[2] also a 24mm by 36mm image size, was prototyped in 1934 and went to market in 1937. K. Nüchterlein’s Kine (Germany, 1936) was the first integrated 35mm SLR to enter the market. Additional Exakta models, all with waist-level finders, were produced up to and during World War II. Another ancestor of the modern SLR camera was the Swiss-made Alpa, which was innovative, and influenced the later Japanese cameras. The first eye-level SLR viewfinder was patented in on August 23, 1943 by Jenő Dulovits, who then designed the first 35 mm camera with one, the Duflex, which used a system of mirrors to provide a laterally correct, upright image in the eye-level viewfinder. The Duflex, which went into serial production in 1948, was also the world’s first SLR with an instant-return (a.k.a. autoreturn) mirror. The first commercially produced SLR that employed a roof pentaprism was the Italian Rectaflex A.1000, shown in full working condition on Milan fair April 1948 and produced from September the same year, thus being on the market one year before the east German Zeiss Ikon VEB Contax S, announced on May 20, 1949, produced from September. The Japanese adopted and further developed the SLR. In 1952, Asahi developed the Asahiflex and in 1954, the Asahiflex IIB. In 1957, the combined the fixed pentaprism and the right-hand thumb wind lever. Nikon, Canon and introduced their first SLRs in 1959 (the F, Canonflex, and Pentamatic, respectively).

Through-the-lens light metering

Main article: Through-the-lens metering

As a small matter of history, the first 35 mm camera (non-SLR) to feature through the lens light metering may have been Nikon, with a prototype rangefinder camera, the SPX. According to the website below, the camera used Nikon 'S' type rangefinder lenses.[3] Through-the-lens light metering is also known as “behind-the-lens metering”. In the SLR design scheme, there were various placements made for the metering cells, all of which used CdS (Cadmium sulfide) photocells. The cells were either located in the pentaprism housing, where they metered light transmitted through the focusing screen; underneath the reflex mirror glass itself, which was ’s design; or in front of the shutter mechanism, which was the design used by Canon with their Canon Pellix. Pentax was the first manufacturer to show an early prototype 35 mm behind-the-lens metering SLR camera, which was named the Pentax Spotmatic. The camera was shown at the 1960 photokina show. However, the first Through- the-lens (TTL) light metering SLR on the market was the 1963 Topcon RE Super, which had the CdS metering cell placed behind the reflex mirror. The mirror had narrow slits cut into the surface to let the light reach the cell providing average metering. Late in the following year, a production model of the Pentax Spotmatic was shown whose CdS cells were on the pentaprism, reading the light off the focusing screen providing average reading, yet keeping the Spotmatic name, but now written in one word. Another clever design appeared in 1965, the Canon Pellix 50 CHAPTER 4. DAY 4 employing a pellicle mirror that is semi-transparent, placing the meter cell on an arm swinging into the lightpass behind the mirror for meter reading. Mamiya Sekor came out with cameras such as the Mamiya Sekor TL and various other versions. Yashica introduced the TL Super. Both of these cameras used M42 screw thread lenses as did the Pentax Spotmatic. Later on introduced their ST-701, then ST-801 and ST-901 cameras. The ST-701 was the first SLR to use a silicon cell , which was more sensitive than CdS and was immune to the memory effect that the CdS cell suffered from in bright sunlight. Gradually, other 35 mm SLR camera manufacturers changed their behind-the-lens meters from CdS cells to Silicon photocells. Other manufacturers responded and introduced their own behind-the-lens metering cameras. Nikon and Miranda, at first, simply upgraded their interchangeable pentaprisms to include behind-the-lens metering (for Nikon F, and Miranda D, F, Fv and G models) and these manufacturers also bought out other camera models with built-in behind- the-lens metering capability, such as the FT and the Miranda Sensorex (which used an external coupling diaphragm). introduced the SRT-101, which used Minolta’s proprietary system they referred to as “CLC”, which was an acronym for “contrast light compensation”, which metered differently from an average metering behind- the-lens camera. Some German manufacturers also introduced cameras such as the Zeiss Ikon Contarex family, which was one of very few 35 mm SLR to use interchangeable film backs. Inexpensive leaf-shutter cameras also benefited from behind-the-lens metering as, Topcon introduced the Auto 100 with front-mount interchangeable lenses designed only for that camera, and one of the Zeiss Ikon Contaflex leaf shutter cameras. Kowa manufactured their SET-R, which had similar specifications. Within months, manufacturers decided to bring out models that provided limited area metering, such as Nikon’s Photomic Tn finder, which concentrated 60% of the CdS cells sensitivity on the inner circle of the focusing screen and 30% on the surrounding area. Canon used spot metering in the unusual Canon Pellix camera, which also had a stationary mirror system that allowed approximately 70% of the light to travel to the film plane and 30% to the photographer’s eye. This system, unfortunately, degraded the native resolution of the attached lens and provided less illumination to the eyepiece. It did have the advantage of having less vibration than other SLR cameras but this was not sufficient to attract professionals to the camera in numbers.

Semi-automatic exposure capabilities

While auto-exposure was commonly used in the early 1960s with various 35 mm fixed lens rangefinder cameras such as the Konica Auto 'S', and other cameras such as the Polaroid Land cameras whose early models used cell meters, auto-exposure for interchangeable lens SLRs was a feature that was largely absent, except for a few early leaf-shutter SLRs such as the Kowa SE-R and Topcon Auto 100. The types of automation found in some of these cameras consisted of the simple programmed shutter, whereby the camera’s metering system would select a mechanically set series of apertures with shutter speeds, one setting of which would be sufficient for the correct exposure. In the case of the above-mentioned Kowa and Topcon, automation was semi-automatic, where the camera’s CDs meter would select the correct aperture only. Autoexposure, technically known as semi-automatic exposure, where the camera’s metering system chooses either the shutter speed or the aperture, was finally introduced by the Savoyflex and popularized by Konishiroku in the 1965 Konica Auto-Reflex. This camera was of the 'shutter-priority' type automation, which meant that the camera selected the correct aperture automatically. This model also had the interesting ability to photograph in 35 mm full-frames or half-frames, all selected by a lever. Other SLRs soon followed, but because of limitations with their lens mounts, the manufacturers of these cameras had to choose 'aperture-priority' automation, where the camera’s metering system selects the correct shutter speed. As one example, Pentax introduced the Electro Spotmatic, which was able to use the then considerable bulk of 42 mm screw-mount lenses produced by various manufacturers. Yashica, another screw-mount camera manufacturer, soon followed. Canon, which produced the FD lens mount (known as the breech-mount; a unique lens mounting system that combines the advantages of screw-mount and bayonet-mount) introduced their shutter priority 35 mm SLR, the Canon EF in 1976 or so. This camera’s build quality was almost the equal of their flagship camera, the Canon F1, and featured a copal-square vertically travelling focal plane shutter that could synchronize electronic flash at shutter speeds up to and including 1/125 of a second, thus making this a good second-body camera for the professional photographer. 4.1. SINGLE-LENS REFLEX CAMERA 51

Nikon at first produced an aperture-priority camera, but later made subtle changes on the inside of their bayonet mount, which allowed for shutter-priority automation without obsoleting the photographers lenses.

Full-program auto-exposure

Full-program auto-exposure soon followed with the advent of the Canon A-1 in 1978. This SLR had a 'P' mode on the shutter speed dial, and a lock on the aperture ring to allow the lens to be put on 'Auto' mode. Other manufacturers soon followed with Nikon introducing the FA, Minolta introducing the X-700 in 1981,[4] and Pentax introducing the Super Program. Olympus, however, continued with 'aperture-priority' automation in their OM system line. The 1970s and 1980s saw steadily increasing use of electronics, automation, and miniaturization, including integrated motor driven film advance with the Konica FS-1 in 1979, and motor rewind functions.

Autofocus

Main article: Autofocus

The first autofocus 35 mm SLR was the Pentax ME-F released in 1981.[5] The Minolta Maxxum 7000, released in 1985, was the first 35 mm SLR with integrated autofocus and motorized film-advance winder, which became the standard configuration for SLR cameras from then on. This development had significant impact on the photographic industry. Some manufacturers discarded their existing lens systems to compete with other manufacturer’s autofocus capability in their new cameras. This was the case for Canon, with its new EOS lens line. Other manufacturers chose to adapt their existing lens systems for autofocus capability, as was the case with Nikon and Pentax. This allowed photographers to continue using their existing lenses, which greatly reduced the cost of upgrading. For example, almost all Nikon lenses from the 1960s and later still function on the current Nikon bodies, only lacking autofocus. Still some manufacturers, notably Leica with its R-system lenses, and Contax with its Zeiss lenses, decided to keep their lens mounts non-autofocus. From the late 1980s competition and technical innovations made 35 mm camera systems more versatile and so- phisticated by adding more advanced light metering capabilities such as spot-metering; limited area metering such as used by Canon with the F1 series; matrix metering as used by Nikon, exposure communication with dedicated electronic flash units. The user interface also changed on many cameras, replacing meter needle displays that were galvanometer-based and thereby fragile, with light-emitting (LEDs) and then with more comprehensive liquid crystal displays (LCDs) both in the SLR viewfinder and externally on the cameras’ top plate using an LCD screen. Wheels and buttons replaced the shutter dial on the camera and the aperture ring on the lens on many models, although some photographers still prefer shutter dials and aperture rings. Some manufacturers introduced on certain lenses to combat camera shake and to allow longer hand-held exposures without using a tripod. This feature is especially useful with long telephoto lenses.

Digital SLRs

Main article: Digital single-lens reflex camera

Canon, Nikon and Pentax have all developed digital SLR cameras (DSLRs) using the same lens mounts as on their respective film SLR cameras. did the same, but in 2006 sold their camera technology to Sony, who now builds DSLRs based on the Minolta lens mount. builds DSLRs based on the Pentax lens mount. Olympus, on the other hand, chose to create a new digital-only SLR standard, adopted later by and Leica. Contax came out with a DSLR model, the Contax N-Digital. This model was too late and too expensive to be competitive with other camera manufacturers. The Contax N-digital was the last Contax to use that maker’s lens system, and the camera, while having impressive features such as a full-frame sensor, was expensive and lacked sufficient write-speed to the memory card for it to be seriously considered by some professional photographers. The digital single-lens reflex camera have largely replaced film SLR’s design in convenience, sales and popularity at the start of 21st century. 52 CHAPTER 4. DAY 4

Typical film SLR viewfinder information

4.1.2 Optical components

A cross-section (or 'side-view') of the optical components of a typical SLR camera shows how the light passes through the lens assembly (1), is reflected by the mirror (2) placed at a 45-degree angle, and is projected on the matte focusing screen (5). Via a condensing lens (6) and internal reflections in the roof pentaprism (7) the image appears in the eyepiece (8). When an image is taken, the mirror moves upwards from its resting position in the direction of the arrow, the focal plane shutter (3) opens, and the image is projected onto the film or sensor (4) in exactly the same manner as on the focusing screen. This feature distinguishes SLRs from other cameras as the photographer sees the image composed exactly as it will be captured on the film or sensor (see Advantages below).

Pentaprisms and penta-mirrors

Most 35 mm SLRs use a roof pentaprism or penta-mirror to direct the light to the eyepiece, first used on the 1948 Duflex[6] constructed by Jenő Dulovits and patented August 1943 (Hungary). With this camera also appeared the first Instant-return mirror. The first Japanese pentaprism SLR was the 1955 Miranda T, followed by the Asahi Pentax, Minolta SR-2, Zunow, Nikon F and the Yashica Pentamatic. Some SLRs offered removable pentaprisms with optional viewfinder capabilities, such as the waist-level finder, the interchangeable sports finders used on the Canon F1 and F1n; the Nikon F, F2, F3, F4 and F5; and the Pentax LX. Another prism design was the porro prism system used in the Olympus Pen F, the Pen FT, the Pen FV half-frame 35 mm SLR cameras. This was later used on the Olympus EVOLT E-3x0 series, the and the Panasonic DMC-L1. A right-angle finder is available that slips onto the eyepiece of most SLRs and D-SLRs and allows viewing through a waist-level viewfinder. There is also a finder that provides EVF remote capability. 4.1. SINGLE-LENS REFLEX CAMERA 53

Focusing screen on Praktica Super TL1000

4.1.3 Shutter mechanisms

Main article: Shutter (photography)

Focal-plane shutters

Main article: Focal-plane shutter

Almost all contemporary SLRs use a focal-plane shutter located in front of the film plane, which prevents the light from reaching the film even if the lens is removed, except when the shutter is actually released during the exposure. There are various designs for focal plane shutters. Early focal-plane shutters designed from the 1930s onwards usually consisted of two curtains that travelled horizontally across the film gate: an opening shutter curtain followed by a closing shutter curtain. During fast shutter speeds, the focal-plane shutter would form a 'slit' whereby the second shutter curtain was closely following the first opening shutter curtain to produce a narrow, vertical opening, with the shutter slit moving horizontally. The slit would get narrower as shutter speeds were increased. Initially these shutters were made from a cloth material (which was in later years often rubberised), but some manufacturers used other materials instead. Nippon Kōgaku (now Nikon Corporation), for example, used titanium foil shutters for several of their flagship SLR cameras, including the Nikon F, F2, and F3. Other focal-plane shutter designs, such as the Copal Square, travelled vertically — the shorter travelling distance of 24 millimetres (as opposed to 36 mm horizontally) meant that minimum exposure and flash synchronisation times could be reduced. These shutters are usually manufactured from metal, and use the same moving-slit principle as horizontally travelling shutters. They differ, though, in usually being formed of several slats or blades, rather than single curtains as with horizontal designs, as there is rarely enough room above and below the frame for a one-piece shutter. Vertical shutters became very common in the 1980s (though Konica, Mamiya, and Copal first pioneered their use in the 1950s and 1960s, and are almost exclusively used for new cameras. Nikon used Copal-made vertical 1 1 plane shutters in their Nikomat/Nikkormat -range, enabling x-sync speeds from ⁄30 to ⁄125 while the only choice for 1 focal plane shutters at that time was ⁄60. Later, Nikon again pioneered the use of titanium for vertical shutters, using 1 a special honeycomb pattern on the blades to reduce their weight and achieve world-record speeds in 1982 of ⁄4000 54 CHAPTER 4. DAY 4

7 8

6 5

1 2 3 4

Cross-section view of SLR system: 1: Front-mount lens (four-element Tessar design) 2: Reflex mirror at 45-degree angle 3: Focal plane shutter 4: Film or sensor 5: Focusing screen 6: Condenser lens 7: Optical glass pentaprism (or pentamirror) 8: Eyepiece (can have diopter correction ability)

1 second for non-sync shooting, and ⁄250 with x-sync. Nowadays most such shutters are manufactured from cheaper aluminium (though some high-end cameras use materials such as carbon-fibre and Kevlar).

Rotary focal-plane shutter One unusual design, the Olympus Pen half-frame 35 mm SLR system, manufactured by Olympus in Japan, used a rotary focal-plane shutter mechanism that was extremely simple and elegant in design. This shutter used titanium foil but consisted of one piece of metal with a fixed opening, which allowed electronic flash synchronisation up to and including its maximum speed of 1/500 of a second – rivalling the capabilities of leaf-shutter systems Another 35 mm camera system that used a rotary shutter, was the Robot Royal cameras, most of which were rangefinder 35 mm cameras. Some of these cameras were full-frame; some were half-frame, and at least one Robot camera produced an unusual square-sized image on the 35 mm frame. The Mercury II, produced in 1946, also used a rotary shutter. This was a half-frame 35mm camera.

Leaf shutters

Another shutter system is the leaf shutter, whereby the shutter is constructed of diaphragm-like blades and can be situated either between the lens or behind the lens. If the shutter is part of a lens assembly some other mechanism is required to ensure that no light reaches the film between exposures. An example of a behind-the-lens leaf shutter is found in the 35 mm SLRs produced by Kodak, with their Retina Reflex camera line; Topcon, with their Auto 100; and Kowa with their SE-R and SET-R reflexes. 4.1. SINGLE-LENS REFLEX CAMERA 55

corrected image to eyepiece

reversed image from reflex mirror

A perspective drawing showing how a roof pentaprism corrects a laterally reversed SLR image.

A primary example of a medium-format SLR with a between-the-lens leaf shutter system would be Hasselblad, with their 500C, 500CM, 500 EL-M (a motorized Hasselblad) and other models (producing a 6 cm square negative). use an auxiliary shutter blind situated behind the lens mount and the mirror system to prevent the fogging of film. Other medium-format SLRs also using leaf shutters include the now discontinued Zenza-Bronica camera system lines such as the Bronica ETRs, the ETRs’i (both producing a 6 × 4.5 cm. image), the SQ and the SQ-AI (producing a 6 × 6 cm image like the Hasselblad), and the Zenza-Bronica G system (6 × 7 cm). Certain Mamiya medium-format SLRs, discontinued camera systems such as the Kowa 6 and a few other camera models also used between-the-lens leaf shutters in their lens systems. Thus, any time a photographer purchased one of these lenses, that lens included a leaf shutter in its lens mount. 1 Because leaf shutters synchronized electronic flash at all shutter speeds especially at fast shutter speeds of ⁄500 of a second or faster, cameras using leaf shutters were more desirable to studio photographers who used sophisticated studio electronic flash systems. Some manufacturers of medium-format 120 film SLR cameras also made leaf-shutter lenses for their focal-plane- shutter models. made at least two such lenses for their Rolleiflex SL-66 medium format which was a focal-plane shutter SLR. Rollei later switched to a camera system of leaf-shutter design (e.g., the 6006 and 6008 reflexes) and their current medium-format SLRs are now all of the between-the-lens shutter design.

4.1.4 Further developments

Since the technology became widespread in the 1970s, SLRs have become the main photographic instrument used by dedicated amateur photographers and professionals. Some photographers of static subjects (such as architec- ture, landscape, and some commercial subjects), however, prefer view cameras because of the capability to control 56 CHAPTER 4. DAY 4

Parts

perspective.[7] With a triple-extension bellows 4” × 5” camera such as the Linhof SuperTechnika V, the photographer can correct certain distortions such as “keystoning”, where the image 'lines’ converge (i.e., photographing a building by pointing a typical camera upward to include the top of the building). Perspective correction lenses are available in the 35 mm and medium formats to correct this distortion with film cameras, and it can also be corrected after the fact with photo when using digital cameras. The photographer can also extend the bellows to its full length, tilt the front standard and perform photomacrography (commonly known as 'macro photography'), producing a sharp image with depth-of-field without the lens diaphram.

4.1.5 Film formats

Main article:

Early SLRs were built for large format photography, but this film format has largely lost favor among professional photographers. SLR film-based cameras have been produced for most film formats as well as for digital formats. These film-based SLRs use the as, this film format offers a variety of emulsions and film sensitivity speeds, usable image quality and a good market cost. 35 mm film comes in a variety of exposure lengths: 20 exposure, 24 exposure and 36 exposure rolls. Medium format SLRs provide a higher-quality image with a negative that can be more easily retouched than the smaller 35 mm negative, when this capability is required. A small number of SLRs were built for APS such as the Canon IX series and the Nikon Pronea cameras. SLRs were also introduced for film formats as small as Kodak’s 110, such as the Pentax Auto 110, which had interchangeable lenses. 4.1. SINGLE-LENS REFLEX CAMERA 57

4.1.6 Common features

Cut-away of a Minolta XE film-based SLR

Other features found on many SLR cameras include through-the-lens (TTL) metering and sophisticated flash control referred to as “dedicated electronic flash”. In a dedicated system, once the dedicated electronic flash is inserted into the camera’s and turned on, there is then communication between camera and flash. The camera’s synchronization speed is set, along with the aperture. Many camera models measure the light that reflects off of the film plane, which controls the flash duration of the electronic flash. This is denoted TTL flash metering. Some electronic flash units can send out several short bursts of light to aid the autofocus system or for wireless communication with off-camera flash units. A pre-flash is often used to determine the amount of light that is reflected from the subject, which sets the duration of the main flash at time of exposure. Some cameras also employ automatic fill-flash, where the flash light and the available light are balanced. While these capabilities are not unique to the SLR, manufacturers included them early on in the top models, whereas the best rangefinder cameras adopted such features later.

4.1.7 Advantages

Many of the advantages of SLR cameras derive from viewing and focusing the image through the attached lens. Most other types of cameras do not have this function; subjects are seen through a viewfinder that is near the lens, making the photographer’s view different from that of the lens. SLR cameras provide photographers with precision; they provide a viewing image that will be exposed onto the negative exactly as it is seen through the lens. There is no parallax error, and exact focus can be confirmed by eye—especially in macro photography and when photographing using long focus lenses. The depth of field may be seen by stopping down to the attached lens aperture, which is possible on most SLR cameras except for the least expensive models. Because of the SLR’s versatility, most manufacturers have a vast range of lenses and accessories available for them. Compared to most fixed-lens compact cameras, the most commonly used and inexpensive SLR lenses offer a wider aperture range and larger maximum aperture (typically f/1.4 to f/1.8 for a 50 mm lens). This allows photographs to be taken in lower light conditions without flash, and allows a narrower depth of field, which is useful for blurring 58 CHAPTER 4. DAY 4

the background behind the subject, making the subject more prominent. “Fast” lenses are commonly used in theater photography, , surveillance photography, and all other photography requiring a large maximum aperture. The variety of lenses also allows for the camera to be used and adapted in many different situations. This provides the photographer with considerably more control (i.e., how the image is viewed and framed) than would be the case with a view camera. In addition, some SLR lenses are manufactured with extremely long focal lengths, allowing a photographer to be a considerable distance away from the subject and yet still expose a sharp, focused image. This is particularly useful if the subject includes dangerous animals (e.g., wildlife); the subject prefers anonymity to being photographed; or else, the photographer’s presence is unwanted (e.g., celebrity photography or surveillance photography). Practically all SLR and DSLR camera bodies can also be attached to telescopes and microscopes via an adapter tube to further enhance their imaging capabilities.

4.1.8 Disadvantages

In most cases, single-lens reflex cameras cannot be made as small or as light as other camera designs—such as rangefinder cameras, autofocus compact cameras and digital cameras with electronic viewfinders (EVF)—owing to the mirror box and pentaprism/pentamirror. The mirror box also prevents lenses with deeply recessed rear elements from being mounted close to the film or sensor unless the camera has a mirror lockup feature; this means that simple 4.1. SINGLE-LENS REFLEX CAMERA 59 designs for wide angle lenses cannot be used. Instead, larger and more complex retrofocus designs are required.

During an exposure, the viewfinder is blocked

The SLR mirror 'blacks-out' the viewfinder image during the exposure. In addition, the movement of the reflex mirror takes time, limiting the maximum shooting speed. The mirror system can also cause noise and vibration. Partially reflective (pellicle) fixed mirrors avoid these problems and have been used in a very few designs including the Canon Pellix and the Canon EOS-1N RS, but these designs introduce their own problems. These pellicle mirrors reduce the amount of light travelling to the film plane or sensor and also can distort the light passing through them, resulting in a less-sharp image. To avoid the noise and vibration, many professional cameras offer a mirror lock-up feature, however, this feature totally disables the SLR’s automatic focusing ability. Electronic viewfinders have the potential to give the 'viewing-experience' of a DSLR (through-the-lens viewing) without many of the disadvantages. More recently, Sony have resurrected the pellicle mirror concept in their "single-lens translucent" (SLT) range of cameras.

Reliability

SLRs vary widely in their construction and typically have bodies made of plastic or magnesium. Most manufacturers do not cite durability specifications, but some report shutter life expectancies for professional models. For instance, the Canon EOS 1Ds MkII is rated for 200,000 shutter cycles and the newer is rated for 300,000 with its exotic carbon fiber/kevlar shutter. Because many SLRs have interchangeable lenses, there is a tendency for dust, sand and dirt to get into the main body of the camera through the mirror box when the lens is removed, thus dirtying or even jamming the mirror movement mechanism or the shutter curtain mechanism itself. In addition, these particles can also jam or otherwise hinder the focusing feature of a lens if they enter into the focusing helicoid. The problem of sensor cleaning has been somewhat reduced in DSLRs as some cameras have a built-in sensor cleaning unit.

Price and affordability

The price of SLRs in general also tends to be somewhat higher than that of other types of cameras, owing to their internal complexity. This is compounded by the expense of additional components, such as flashes or lenses. The initial investment in equipment can be prohibitive enough to keep some casual photographers away from SLRs, although the market for used SLRs has become larger particularly as photographers migrate to digital systems. 60 CHAPTER 4. DAY 4

4.1.9 Future of SLRs

The digital single-lens reflex camera has largely replaced the film SLR for its convenience, sales, and popularity at the start of 21st century. These cameras are currently the marketing favorite among advanced amateur and professional photographers. Film-based SLRs are still used by a niche market of enthusiasts and format lovers.[8]

4.1.10 See also

• Asahi Pentax • Fujifilm

• Lenses for SLR and DSLR cameras • Scheimpflug principle

• Zeiss Ikon

4.1.11 References

[1] One was patented in 1861 (Thomas Sutton), but it is not clear if a second example was ever produced; Calvin Rae Smith’s design of a Patent Monocular Duplex camera was advertised and sold. Spira, The History of Photography, 119.

[2] A. O. Gelgar’s Sport

[3] Stephen, Gandy. “Nikon Shibata Book”. Stephen Gandy’s CameraQuest. Retrieved 2008-06-08.

[4] “The Rokkor Files the minolta x-700”. The Rokkor Files. November 23, 2010. Retrieved 2010-11-23.

[5] Pentax Imaging Company. “History of Innovations 1980–1989”. Pentax history of innovations. Retrieved 2006-10-22.

[6] “Article at Photopedia”. Bichkov.com. 2008-01-23. Retrieved 2013-10-15.

[7] Tal, Guy. “Introduction to Large Format”. Nature Photographers Online Magazine. Retrieved 2007-08-28.

[8] ARRI, , and Aaton Cease Production of Film Cameras; Will Focus Exclusively on Digital

4.1.12 Further reading

• Spira, S. F. The History of Photography as Seen through the Spira Collection. New York: Aperture, 2001. ISBN 0-89381-953-0. • Antonetto, Marco: “Rectaflex - The Magic Reflex”. Nassa Watch Gallery, 2002. ISBN 88-87161-01-1

4.1.13 External links

• Photography in Malaysia’s Contax History, Part II. • 'Innovative Cameras’ by Massimo Bertacchi Chapter 5

Day 5

5.1 Mirrorless interchangeable-lens camera

EVIL redirects here, as an acronym for Electronic Viewfinder Interchangeable Lens.

Leica M9 digital mirrorless full frame system camera with a rangefinder

A mirrorless interchangeable lens camera is a digital camera with an interchangeable lens. A mirrorless camera uses an image sensor to provide an image to the electronic viewfinder (EVF). It is called mirrorless since it does not have a movable mirror in the optical path. Compared to single-lens reflex cameras (SLR), mirrorless cameras can be made simpler, smaller and lighter because they do not have an optical viewfinder. Such a viewfinder is composed of a mirrorhousing, a movable mirror, or

61 62 CHAPTER 5. DAY 5

Sony A7R digital mirrorless full frame system camera with an EVF

a viewing prism with reticle. Neither do they need a secondary autofocus mirror, an autofocus sensor array and a separate light metering sensor. Since mobile phones with cameras, compact cameras, superzoom cameras today all are mirrorless cameras, it is essentially only the DSLR cameras, with emphasis on the R (Reflex) which are cameras with movable mirrors. Mirrorless cameras have until recently had two challenges keeping them from competing with top of the line DSLRs. The initial challenge was to provide an EVF with the resolution, clarity and response of direct optical viewing. The second challenge has been that the contrast detect autofocus (CDAF) initially used in mirrorless cameras requires about twice the time to acquire focus compared to that of phase detect autofocus (PDAF). Professional photographers covering sports and news events have therefore been among the last to embrace the mirrorless cameras. The latest generation mirrorless cameras, however, have PDAF built into the image sensor offering fully competitive and accurate autofocus and many times faster continuous shooting with continuous autofocus than DSLRs. With high quality images being available even from smaller sensors a new distinction other than camera price is available to photographers. As a rule, to professionally photograph studio objects, landscapes or architecture requiring rich and realistic images, a camera with a full frame or a medium format sensor is preferred. Lenses required and used for this are typically in the 20 to 200 mm focal range. With the same requirement for image quality, sports and then requires focal lengths from 600 to 800 mm or more. Mirrorless system cameras with smaller, high resolution sensors can here offer the advantage of the same final image coverage using shorter focal 5.1. MIRRORLESS INTERCHANGEABLE-LENS CAMERA 63

Olympus OM-D E-M1 Mark II digital mirrorless micro 4/3 system camera with an EVF length, lighter lenses because of the so-called “” of the smaller sensor. This of course requires that the smaller sensor has a high enough pixel density to offer a final resolution equal to or better than what can be cropped out of the image from a larger sensor using the same, shorter focal length lens.

5.1.1 New technologies in mirrorless cameras

IBIS

Whereas image stabilizing techniques (IS), also called vibration reduction (VR), have been available in long focal length lenses for DSLRs for some time, recent mirrorless cameras are offering in body image stabilization (IBIS) where the image sensor moves inside the camera to keep the image steady on the image sensor, counteracting any undesirable vibration or shaking of the camera during handheld exposures. The manufacturer Olympus combines this with vibration reduction in the lens to achieve five axis of total vibration reduction including two axis of rotation. The result is claimed to enable sharp and shake free handheld exposures as long as several seconds.

Silent shutter

Electronic first and second curtain shutters for a totally quiet, electronic exposure is also becoming common. With sensor scan times down to 1/60 of a second, totally quiet electronic shutters are now useful even during short exposures of subjects in some motion without distorting the image. 64 CHAPTER 5. DAY 5

Hasselblad X1D digital mirrorless medium format system camera with an EVF

Continuous autofocus

The ability of a camera with autofocus to re-focus between rapid shots in a series of continuous exposures (CAF) has up until recently been possible only with high end DSLRs, and even then, because of the limited speed of the mirror mechanism, the continuous shooting speed has been limited to around half a dozen shots per second. Although autofocus speed has been the Achilles heel of the mirrorless camera, several manufacturers today boost continuous shooting with continuous refocusing between exposures at rates up to 18 frames per second with silent, electronic shutter and up to 10 frames per second with mechanical shutter.

High dynamic range

In camera automation of high dynamic range photography (HDR) is being offered. The camera takes a series of shots under varying exposures and combines them in the camera into one high dynamic range image.

High resolution image

Though the resolution of any sensor is limited, the IBIS mechanism in the camera allows the camera to move the image sensor in steps smaller than the image sensor pixel size to produce a multi exposure image with a resolution higher than the image sensor itself. Both high dynamic range (HDR) and high resolution images are best captured while the camera is mounted on a tripod and triggered remotely. 5.1. MIRRORLESS INTERCHANGEABLE-LENS CAMERA 65

Fujifilm GFX 50S digital mirrorless medium format system camera with an EVF

Focus stacking

Many mirrorless cameras are also capable of producing an image with seemingly infinite . The tech- nique involves several exposures executed at various focal planes and combined in the camera to an image with seemingly infinite depth of focus.

Touch screen

Touch screen technology has finally been adopted by the camera industry. It is now easier to maneuver within menus and between commands thanks to intuitive touch screen technology being applied to mirrorless camera LCD displays.

5.1.2 Market

Because of advances made in digital image sensor technology and electronic viewfinders, electronics are replac- ing most of the mechanics that once were necessary in film SLRs for framing an image through either an optical rangefinder or an optical viewfinder based on the single lens reflex mirror concept. It is likely that this evolution will continue offering even smaller and more capable mirrorless cameras in the future. One of the pioneers in the field has been Sony Corporation who supplies a large number of other camera manufacturers with image sensors. Sony also sells cameras of their own, especially to show off advancements in their sensor and processing technology, often releasing improved designs at a rapid rate while simultaneously carefully limiting how they can and want to compete with their sensor customers. Both Canon and Nikon, the two biggest camera manufacturers, have been struggling financially with the loss of sales of simpler and less expensive cameras to the manufacturers of camera enabled mobile phones. As a result, both Canon and Nikon have been slow in picking up on the trend toward mirrorless system cameras. However, once the market shows them where it is going we are likely to see mirrorless system cameras from both Canon and Nikon as well. 66 CHAPTER 5. DAY 5

Other early players in the mirrorless system camera market are shown in the Systems Comparison below. Whereas mobile phones with cameras, point and shoot cameras, compact cameras, superzoom cameras, compact mirrorless system cameras and mirrorless system cameras today all exist in the marketplace a trend toward elimina- tion of the less successful categories is noticeable. While mobile phones with cameras have taken over the lion’s share of the point and shoot and compact camera market, more advanced mirrorless cameras with a non-interchangeable are still being marketed. However, even more useful and common are today mirrorless cameras with a non-interchangeable , whereas the big category is likely to become mirrorless system cameras with in- terchangeable lenses. An interesting trend toward the difference between the categories compact mirrorless system cameras and professional mirrorless system cameras is that while casual users may prefer a pocket size camera, some- times with a collapsible or pancake lens, professional users demand a more substantial camera grip with good balance and comfortable ergonomics plus a battery for all day use, making new, professional mirrorless system cameras slightly larger than their compact siblings.

5.1.3 History

In 2013 Mirrorless system cameras constituted about five percent of total camera shipments.[1] In 2015, they ac- counted for 26 percent of system camera sales outside the Americas, and 16 percent in the U.S.[2] 2004-2008. The category started with Epson R-D1 (released in 2004), followed by (released September 2006, which isn't actually a “mirrorless” but a rangefinder camera, a system of focussing dating back to 1933 and the release of the Leica III, itself a development of the 1932 Leica II) and then the , whose first camera was the Panasonic DMC-G1, released in Japan in October 2008.[3] 2009-2010. A more radical design is the GXR (November 2009), which features, not interchangeable lenses, but interchangeable lens units – a sealed unit of a lens and sensor.[4][5][6] This design is comparable but distinct to MILCs, and has so far received mixed reviews, primarily due to cost; As of 2012 the design has not been copied. Following the introduction of the Micro Four Thirds, several other cameras were released in the system by Panasonic and Olympus, with the Olympus PEN E-P1 (announced June 2009) being the first in a compact size (pocketable with a small lens). The Samsung NX10 (announced January 2010) was the first camera in this class not using the Micro Four Thirds system – rather a new, proprietary lens mount (Samsung NX-mount). The Sony Alpha NEX-3 and NEX-5 (announced May 14, 2010, for release July 2010) saw the entry of Sony into the market, again with a new, proprietary lens mount (the Sony E-mount), though with LA-EA1 and LA-EA2 adapters for the legacy Minolta A-mount. 2011. In June 2011, Pentax announced the 'Q' mirrorless interchangeable lens camera and the 'Q-mount' lens system. The original Q series featured a smaller 1/2.3 inch 12.4 megapixel CMOS sensor.[7] The Q7, introduced in 2013, has a slightly larger 1/1.7 inch CMOS sensor with the same megapixel count.[8] In September 2011, Nikon announced their Nikon 1 system which consists of the and cameras and lenses. The V1 features an electronic viewfinder.[9] 2012. The Fujifilm X-Pro1, announced in January 2012, was the first non-rangefinder mirrorless with a built-in optical viewfinder. Its hybrid viewfinder overlays electronic information, including shifting framelines to compensate for parallax. Its 2016 successor, the X-Pro2, features an updated version of this viewfinder. Beyond the interest to consumers, mirrorless has created significant interest in camera manufacturers, having potential to be an alternative in the high-end camera market. Significantly, mirrorless has fewer moving parts than DSLRs, and are more electronic, which plays to the strengths of electronic manufacturers (such as Panasonic, Samsung and Sony), while undermining the advantage that existing camera makers have in precision mechanical engineering. Sony’s entry level full frame mirrorless α7 II camera has a 24MP 5 axis stabilised sensor yet is more compact and lower in cost than any full frame sensor DSLR. Nikon announced the with a 1” sensor on September 21, 2011. It was a high-speed mirrorless which according to Nikon featured world’s fastest autofocus and world’s fastest continuous shooting speed (60 fps) among all cameras with interchangeable lenses including DSLRs.[10] Canon was the last of the major makers of DSLRs, announcing the Canon EOS M in 2012 with APS-C sensor and 18 mm registration distance similar to the one used by NEX. In a longer-term Olympus decided that mirrorless may replace DSLRs entirely in some categories with Olympus America’s DSLR product manager speculating that by 2012, Olympus DSLRs (the Olympus E system) may be mirrorless, though still using the Four Thirds System (not Micro Four Thirds).[11] 5.1. MIRRORLESS INTERCHANGEABLE-LENS CAMERA 67

Panasonic UK’s Lumix G product manager John Mitchell while speaking to the Press at the 2011 “Focus on Imaging” show in Birmingham, reported that Panasonic “G” camera market share was almost doubling each year, and that UK Panasonic “G” captured over 11% of all interchangeable camera sales in the UK in 2010, and that UK “CSC” sales made up 23% of the Interchaneable lens market in the UK, and 40% in Japan.[12] As of May 2010, interchangeable-lens camera pricing is comparable to and somewhat higher than entry-level DSLRs, at US$550 to $800, and significantly higher than high-end compact cameras. As of May 2011, interchangeable-lens camera pricing for entry mirrorless appears to be lower than entry-level DSLRs in some markets e.g. the U.S. Sony announced 2011 sales statistics in September 2012, which showed that mirrorless had 50% of the interchange- able lens market in Japan, 18% in Europe, and 23% worldwide. Since that time Nikon has entered the mirrorless market, amongst other new entries. 2013. In a down-trend world camera market, mirrorless also suffered, but not much and can be compensated with increase by about 12 percent of 2013 sales in popular mirrorless domestic (Japan) market.[13] However, mirrorless has taken longer catch on in Europe and North America—according to Japanese photo industry sources, mirrorless made up only 11.2% of interchangeable-lens cameras shipped to Europe in the first nine months of 2013, and 10.5% in the U.S. in the same period.[14] Also, an industry researcher determined that Mirrorless sales in the U.S. fell by about 20% in the three weeks leading up to December 14, 2013—which included the key Black Friday shopping week; in the same period, DSLR sales went up 1%.[14] In 2015, mirrorless is gaining market share in North America, while DSLR is falling, showing 16.5% $ value growth rates for mirrorless while DSLR is falling by 17% in $ value sales. In Japan, mirrorless at times outsells DSLR. Despite lowering DSLR prices 2015 sales figures due in January 2015 will show further increases of mirrorless compared to DLSRs in the ILC market. In 2015, mirrorless-cameras accounted for 26 percent of interchangeable-lens camera sales outside the Americas, although a lesser share of 16 percent in the U.S., but still [2] a huge increase in interchangeable lens camera market share in only two years.[15] 2015. 2015 statistics show that overall camera sales have fallen to one third of those of 2010, due to compact cameras being substituted by camera capable mobile phones. This means that overall share of camera sales is seeing ILC market share increasing, with world volumes showing ILC having 30% for overall camera sales, of which DSLR had 77% and mirrorless 23%.[16] In the Americas in 2015, DSLR annual sales in dollars are now falling by 16% per annum, while mirrorless sales over the same 12-month period have increased by 17%.[17] Hence the Mirrorless market share of interchangeable lens cameras has more than doubled in two years. 2016. Late 2016 announced the introduction of their OM-D E-M1 Mark II, a successor to the earlier and successful Mark I. The Mark II model retains a micro 4/3 image sensor of 17.3x13 mm featuring 20.4 MP resolution and represents a new generation of mirrorless cameras competitive with and in many respects superior to DSLR cameras. It is likely that this development will be continued by other camera manufacturers into larger APS-C, full format and medium format mirrorless system cameras.

•

• Ricoh GXR 68 CHAPTER 5. DAY 5

• Samsung NX10

• Panasonic Lumix DMC-G1

5.1.4 Systems comparison

5.1.5 References

[1] “Camera shipments continue to fall”. Retrieved August 12, 2013.

[2] DPReview June 3, 2015 http://www.dpreview.com/articles/6223902518/sony-rides-wave-of-us-mirrorless-sales-surge

[3] “Panasonic Lumix G1 reviewed”. Digital Photography Review.

[4] Joinson, Simon (October 2009), Ricoh GXR Preview, DPReview.

[5] Rehm, Lars; Joinson, Simon; Westlake, Andy (March 2010), Ricoh GXR/A12 50mm Review, DPReview.

[6] Rehm, Lars; Joinson, Simon (March 2010), Ricoh GXR/S10 24-72mm F2.5–4.4 VC Review, DPReview.

[7] Pentax Q small-sensor mirrorless camera announced and previewed, DPReview, June 23, 2011

[8] Johnson, Allison (August 2013). “Pentax Q7 Review”. Digital Photography Review. Retrieved October 8, 2013.

[9] Nikon announces Nikon 1 system with V1 small sensor mirrorless camera, DPReview, September 21, 2011.

[10] Nikon announces Nikon 1 system with V1 small sensor mirrorless camera Dpreview

[11] Olympus E system mirrorless in two years. Probably., Monday February 22, 2010, Damien Demolder

[12] “Panasonic primed for Canon and Nikon fight news”. . March 9, 2011. Retrieved October 30, 2011.

[13] “Mirrorless cameras offer glimmer of hope to makers”. Retrieved December 31, 2013.

[14] Knight, Sophie; Murai, Reiji (December 31, 2013). “The Last, Best Hope For A Digital Camera Rebound Is Failing”. Business Insider. Reuters. Retrieved March 16, 2014.

[15] http://www.slideshare.net/arancaresearch/digital-camera-44303531

[16] Global Market Share Digital Cameras http://www.slideshare.net/arancaresearch/digital-camera-44303531

[17] Sony Rides Wave of Mirrorless US Sales Sales Surge http://www.dpreview.com/articles/6223902518/sony-rides-wave-of-us-mirrorless-sales-surge

[18] “Put Your Creativity Into Motion With The New EOS M Digital Camera” (Press release). Canon U.S.A., Inc. July 23, 2012. Retrieved July 24, 2012.

[19] Westlake, Andy (July 23, 2012). “Canon EOS M hands-on preview”. Digital Photography Review. Retrieved July 24, 2012.

[20] Westlake, Andy (April 24, 2014). “ (Typ 701) specifications”. Leica T (Typ 701) First Impressions Review. Digital Photography Review. Retrieved September 10, 2016. 5.1. MIRRORLESS INTERCHANGEABLE-LENS CAMERA 69

[21] admin, on June 23, 2011 (June 23, 2011). “Pentax Q”. Photoclubalpha. Retrieved October 30, 2011.

[22] “Pentax Q Compact System Camera – Initial Test”. Imaging-resource.com. Retrieved October 30, 2011.

• Fairlie, Rik (April 7, 2010). “A Digital Camera That Swaps Lenses, Priced to Please”. . ISSN 0362-4331. Retrieved May 16, 2010. Chapter 6

Day 6

6.1 Twin-lens reflex camera

A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective or “taking lens” (the lens that takes the picture), while the other is used for the viewfinder system, which is usually viewed from above at waist level. In addition to the objective, the viewfinder consists of a 45-degree mirror (the reason for the word reflex in the name), a matte focusing screen at the top of the camera, and a pop-up hood surrounding it. The two objectives are connected, so that the focus shown on the focusing screen will be exactly the same as on the film. However, many inexpensive “pseudo” TLRs are fixed-focus models. Most TLRs use leaf shutters with shutter speeds up to 1/500th sec with a B setting. For practical purposes, all TLRs are film cameras, most often using 120 film, although there are many examples which used 620 film, 127 film, and 35mm film. No general-purpose digital TLR cameras exist, since the heyday of TLR cameras ended long before the era of digital cameras.

6.1.1 History

Double-lens cameras were first developed around 1870, due to the realization that having a second lens alongside the taking lens would mean that one could focus without having to keep swapping the ground glass screen for the plate, reducing the time required for taking a picture.[1] This sort of approach was still used as late as the 1960s, as the Koni-Omegaflex[2] testifies. The TLR camera was thus an evolution. Using a reflex mirror to allow viewing from above also enabled the camera to be held much more steadily than if it were to be held in the hand. The same principle of course applied to SLR cameras, but early SLR cameras caused delays and inconvenience through the need to move the mirror out of the focal plane to allow light to pass to the plate behind it. When this process was automated, the movement of the mirror could cause shake in the camera and blur the image. The London Stereoscopic Co’s “Carlton” model is claimed to have been the first off-the-shelf TLR camera, dating from 1885.[3] The major step forward to mass marketing of the TLR came with the Rolleicord and then Rolleiflex in 1929, developed by Franke & Heidecke in Germany. The Rolleiflex was widely imitated and copied and most mass-market TLR cameras owe much to its design. It is said that Reinhold Heidecke had the inspiration for the Rollei TLRs whilst undertaking photography of enemy lines from the German trenches in 1916, when a periscopic approach to focusing and taking photos radically reduced the risk to the photographer from sniper fire.[4] TLRs are still manufactured in Germany by DHW Fototechnik, the successor of Franke & Heidecke in three versions.[5]

6.1.2 Features

Higher-end TLRs may have a pop-up magnifying glass to assist the user in focusing the camera. In addition, many have a “sports finder” consisting of a square hole punched in the back of the pop-up hood, and a knock-out in the

70 6.1. TWIN-LENS REFLEX CAMERA 71 front. Photographers can sight through these instead of using the matte screen. This is especially useful in tracking moving subjects such as animals or race cars, since the image on the matte screen is reversed left-to-right. It is nearly impossible to accurately judge composition with such an arrangement, however. Mamiya's C-Series, introduced in the 1960s, the C-3, C-2, C-33, C-22 and the Mamiya C330 and Mamiya C220 along with their predecessor the Mamiyaflex,[6] are the main conventional TLR cameras to feature truly interchangeable lenses.[7] “Bayonet-mount” TLRs, notably Rolleis & Yashicas, had both wide-angle and tele supplementary front add-ons, with Rollei’s Zeiss Mutars being expensive but fairly sharp. Rollei also made separate TLRs having fixed wide-angle or tele lenses: the Tele Rollei and the Rollei Wide, in relatively limited quantities; higher sharpness, more convenient (faster than changing lenses) if one could carry multiple cameras around one’s neck, but much more costly than using 1 camera with supplements. The Mamiya TLRs also employ bellows focusing, making extreme closeups possible. Many TLRs used front and back cut-outs in the hinged top hood to provide a quick-action finder for sports and action photography. Late model Rollei Rolleiflex TLRs introduced the widely copied additional feature of a second- mirror “sports finder”. When the hinged front hood knock-out is moved to the sports finder position a secondary mirror swings down over the view screen to reflect the image to a secondary magnifier on the back of the hood, just below the direct view cutout. This permits precise focusing while using the sports finder feature. The magnified central image is reversed both top-to-bottom and left-to-right. This feature made Rolleis the leading choice for press photographers during the 1940s to 1960s.[8]

6.1.3 Advantages

• A primary advantage of the TLR is in its mechanical as compared to the more common single-lens reflex cameras. The SLR must employ some method of blocking light from reaching the film during focusing, either with a focal plane shutter (most common) or with the reflex mirror itself. Both methods are mechanically complicated and add significant bulk and weight, especially in medium-format cameras.

• Because of their mechanical simplicity, TLR cameras are considerably cheaper than SLR cameras of similar optical quality, as well as inherently less prone to mechanical failure.

• SLR shutter mechanisms are comparatively noisy. Most TLRs use a leaf shutter in the lens. The only mechan- ical noise during exposure is from the shutter leaves opening and closing.

• TLRs are practically different from single-lens reflex cameras (SLR) in several respects. First, unlike virtually all film SLRs, TLRs provide a continuous image on the finder screen. The view does not black out during exposure.

• Since a mirror does not need to be moved out of the way, the picture can be taken much closer to the time the shutter is actuated by the photographer, reducing so-called shutter lag. This trait, and the continuous viewing, made TLRs the preferred camera style for dance photography[9]

• The separate viewing lens is also very advantageous for long-exposure photographs. During exposure, an SLR’s mirror must be retracted, blacking out the image in the viewfinder. A TLR’s mirror is fixed and the taking lens remains open throughout the exposure, letting the photographer examine the image while the exposure is in progress. This can ease the creation of special lighting or transparency effects.

• TLRs are also ideal for candid camera shots where an eye-level camera would be conspicuous. A TLR can be hung on a neck strap and the shutter fired by cable release.

• Models with leaf shutters within the lens, rather than focal-plane shutters installed inside the camera body, can synchronize with flash at higher speeds than can SLRs. Flashes on SLRs usually cannot synchronize accurately when the shutter speed is faster than 1/60th of a second and occasionally 1/125th. Some higher quality DSLRs can synchronize at up to 1/500th of a second. Leaf shutters allow for flash synchronization at all shutter speeds.

• Owing to the availability of medium-format cameras and the ease of image composition, the TLR was for many years also preferred by many portrait studios for static poses.

• Extreme dark photographic filter like the opaque Wratten 87 can be used without problems, as they cover and thus darken only the taking lens. The image in the viewfinder stays bright. 72 CHAPTER 6. DAY 6

6.1.4 Disadvantages

• Few TLR cameras offered interchangeable lenses and none were made with a zoom lens. In systems with interchangeable lenses, such as the Mamiya, the fixed distance between the lenses sets a hard limit on their size, which precludes the possibility of large aperture long-focus lenses.

• Because the photographer views through one lens but takes the photograph through another, parallax error makes the photograph different from the view on the screen. This difference is negligible when the subject is far away, but is critical for nearby subjects. Parallax compensation may be performed by the photographer in adjustment of the sight line while compensating for the framing change, or for highly repeatable accuracy in tabletop photography (in which the subject might be within a foot (30 cm) of the camera), devices are available that move the camera upwards so that the taking lens goes to the exact position that the viewing lens occupied. [Mamiya’s very accurate version was called the Para-mender, and mounted on a tripod.] Some TLRs like the Rolleiflex (a notable early example is the Voigtländer Superb of 1933[10]) also came with - more or less complex - devices to adjust parallax with focussing.

• It is generally not possible to preview depth of field, as one can with most SLRs, since the TLR’s viewing lens usually has no diaphragm. Exceptions to this are the Rolleiflex, the Mamiya 105 D and 105 DS lenses, which have a depth of field preview.

• As the viewfinder of a TLR camera requires the photographer to look down toward the camera, it is inconvenient to frame a photo with a subject that requires the camera to be positioned above the photographer’s chest unless a tripod is used. In these cases, the camera may be positioned with the lenses oriented horizontally. Due to the TLR’s square format, the composition need not be altered.

• The image in the waist-level finder is reversed 'left to right' which can make framing a photograph difficult, especially for an inexperienced user or with a moving subject. With high-quality TLRs like the Rolleiflex and the Mamiya C220/C330 the waist-level finder can be replaced by an eye-level finder, using a roof pentaprism or pentamirror to correct the image while making it viewable through an eyepiece at the rear of the camera.

• The design of the leaf shutter limits almost all TLRs to a maximum shutter speed between 1/100th and 1/500th of a second.

• Certain photographic filters are inconvenient without line of sight through the taking lens - notably, graduated neutral density filters are hard to use with a TLR, as there is no easy way to position the filter accurately.

6.1.5 Film formats

6x6 format

The typical TLR is medium format, using 120 roll film with square 6×6 cm images. Presently, the Chinese Seagull Camera is still in production along with Lomography’s Lubitel, but in the past, many manufacturers made them. DHW-Fototechnik GmbH, continues to make the Rolleiflex TLR, as well (http://www.dhw-fototechnik.de/en/rolleiflex-tlr. html). The Ciro-flex produced by Ciro Cameras Inc. rose dramatically in popularity due in large part to the inability to obtain the German Rollei TLRs during World War II. The Ciro-flex was widely accessible, inexpensive, and pro- duced high quality images.[11] Models with the Mamiya, Minolta and Yashica brands are common on the used-camera market, and many other companies made TLRs that are now classics. The series TLRs had interchange- able lenses, allowing focal lengths from 55mm (wide angle) to 250mm (telephoto) to be used. The bellows focusing of these models also allowed extreme closeups to be taken, something difficult or impossible with most TLRs. The simple, sturdy construction of many TLRs means they have tended to endure the years well. Many low-end cameras used cheap shutters however, and the slow speeds on these often stick or are inaccurate.

127 format

There were smaller TLR models, using 127 roll film with square 4×4 cm images, most famous the “Baby” Rolleiflex and the Yashica 44. The TLR design was also popular in the 1950s for inexpensive fixed focus cameras such as the Kodak Duaflex and Argus 75. 6.1. TWIN-LENS REFLEX CAMERA 73

35mm format

Though most used medium format film, a few 35mm TLRs were made, the very expensive Contaflex TLR being the most elaborate, with interchangeable lenses and removable backs.

Subminiature format

The smallest photography TLR camera using 35mm film is the Swiss-made Tessina, using perforated 35mm film reloaded into special Tessina cassette, forming images of 14×21 mm. Goerz Minicord twin lens reflex made 10x10mm format on double perforated 16mm film in metal cassette.6 Element Goerz Helgor F2 lens, metal focal plane shutter B,10,25,50,100 and 400. Viewing lens uses pentaprism reflex optics for the viewing lens. Picture format 10x10mm on double perforated 16mm film Minox rebadged Sharan Rolleflex 2.8F classic retro TLR film camera, 1/3 scale 6x6 Rolleiflex TLR, using Minox cassette image size 8x11mm, 15mm F5.6 glass triplet lens, mechanical shutter 1/250 sec. Japan made Gemflex, a twin lens reflex using 17.5mm paper back roll film It has been argued that the medical gastroscopy camera, the Olympus Gastro Camera[12] is technically the smallest TLR device.

6.1.6 Notes

[1] Holmes, Edward (1978). An Age Of Cameras. p. 11. ISBN 978-0-8524-2346-2. Retrieved 27 June 2015.

[2] http://www.tlr-cameras.com/Japanese/slides/Koni-Omegaflex.html

[3] http://www.tlr-cameras.com/history.htm

[4] “Complete Collector’s Guide to the Rollei TLR, Ian Parker, Hove Photo Books, Jersey, 1993

[5] “DHW Fototechnik unveils new version of the classic Rolleiflex TLR camera”.

[6] Www.Tlr-Cameras.Com/Mamiya

[7] However, the (6×6 cm) Koniflex (from Konica) is one of several others sold in small volumes to have a supplementary tele lens, and the (6×7 cm) Koni-Omegaflex (cited above) can be used as a TLR with an optional finder and has interchangeable lenses.

[8] Ian Parker: Complete Rollei Collector’s Guide, 1993

[9] Dance Movement Photography (DOC format)

[10] http://www.tlr-cameras.com/German/Voigtlander.html

[11] Mike Roskin, “Occam’s Ciroflex,” Camera Shopper, May, 1995, 38.

[12] http://www.tlr-cameras.com/misc/Gastro.htm

6.1.7 External links

• DHW Fototechnik (Manufacturer of current Rolleiflex TLR cameras and repair) English and German • Rolleiflex Repair Shops and Related Services World Wide by Ferdi Stutterheim

• Paepke Fototechnik (Repair and maintenance of Rolleiflex cameras and other Rollei equipment) English and German

• TLR Cameras Website by Barry Toogood (Large collection of 120/220 film TLRs and some history and other models) English 74 CHAPTER 6. DAY 6

The front of a Kinaflex twin-lens reflex camera. The focus rings of the two lenses are coupled with gears around their circumference in this simple design. 6.1. TWIN-LENS REFLEX CAMERA 75

Sketch of an early-20th-century twin-lens reflex camera 76 CHAPTER 6. DAY 6

The classic Rolleiflex TLR 6.1. TWIN-LENS REFLEX CAMERA 77

1957 Kodak Duaflex IV, an inexpensive fixed-focus TLR 78 CHAPTER 6. DAY 6

Yashica Mat 124 G 6.1. TWIN-LENS REFLEX CAMERA 79

Goerz Minicord III twin lens reflex 16mm camera 80 CHAPTER 6. DAY 6

Tessina TLR 6.1. TWIN-LENS REFLEX CAMERA 81

Sharan Rolleiflex 2.8F TLR Minox film camera Chapter 7

Day 7

7.1 Image sensor

An image sensor or imaging sensor is a sensor that detects and conveys the information that constitutes an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, medical imaging equipment, night vision equipment such as thermal imaging devices, radar, sonar, and others. As technology changes, digital imaging tends to replace analog imaging. Early analog sensors for visible light were video camera tubes. Currently, used types are semiconductor charge- coupled devices (CCD) or active pixel sensors in complementary metal–oxide–semiconductor (CMOS) or N-type metal-oxide-semiconductor (NMOS, Live MOS) technologies. Analog sensors for invisible radiation tend to involve vacuum tubes of various kinds. Digital sensors include flat panel detectors.

7.1.1 CCD vs CMOS technology

Today, most digital cameras use a CMOS sensor, because CMOS sensors perform better than CCDs. An example is the fact that they incorporate an , helping reduce costs. CCD is still in use for cheap low entry cameras, but weak in .[1] Both types of sensor accomplish the same task of capturing light and converting it into electrical signals. Each cell of a CCD image sensor is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges in the line of pixels nearest to the (one or more) output amplifiers are amplified and output, then each line of pixels shifts its charges one line closer to the amplifier(s), filling the empty line closest to the amplifiers(s). This process is then repeated until all the lines of pixels have had their charge amplified and output.[2] A CMOS image sensor has an amplifier for each pixel compared to the few amplifiers of a CCD. This results in less area for the capture of photons than a CCD, but this problem has been overcome by using microlenses in front of each photodiode, which focus light into the photodiode that would have otherwise hit the amplifier and not be detected.[3] Some CMOS imaging sensors also use Back-side illumination to increase the number of photons that hit the photodiode. CMOS sensors can potentially be implemented with fewer components, use less power, and/or provide faster readout than CCD sensors.[4] They are also less vulnerable to static electricity discharges. Another hybrid CCD/CMOS architecture, sold under the name “sCMOS,” consists of CMOS readout integrated circuits (ROICs) that are bump bonded to a CCD imaging substrate – a technology that was developed for staring arrays and now adapted to silicon-based detector technology.[5] Another approach is to utilize the very fine dimensions available in modern CMOS technology to implement a CCD like structure entirely in CMOS technology. This can be achieved by separating individual poly-silicon gates by a very small gap. These hybrid sensors are still in the research phase and can potentially harness the benefits of both CCD and CMOS imagers.[6]

82 7.1. IMAGE SENSOR 83

A CCD image sensor on a flexible circuit board

7.1.2 Performance

See also: EMVA1288

There are many parameters that can be used to evaluate the performance of an image sensor, including dynamic range, signal-to-noise ratio, and low-light sensitivity. For sensors of comparable types, the signal-to-noise ratio and dynamic range improve as the size increases.

7.1.3 Color separation

There are several main types of color image sensors, differing by the type of color-separation mechanism:

• Bayer filter sensor, low-cost and most common, using a color filter array that passes , green, or light to selected pixel sensors, forming interlaced grids sensitive to red, green, and blue – the missing color samples 84 CHAPTER 7. DAY 7

A micrograph of the corner of the photosensor array of a ‘’ digital camera

are interpolated using a demosaicing algorithm. In order to avoid interpolated color information, techniques like color co-site sampling use a piezo mechanism to shift the color sensor in pixel steps. The Bayer filter sensors also include back-illuminated sensors, where the light enters the sensitive silicon from the opposite side of where the transistors and metal are, such that the metal connections on the devices side are not an obstacle for the light, and the efficiency is higher.[7][8]

• , using an array of layered pixel sensors, separating light via the inherent wavelength- dependent absorption property of silicon, such that every location senses all three color channels.

• 3CCD, using three discrete image sensors, with the color separation done by a dichroic prism.

7.1.4 Specialty sensors

Special sensors are used in various applications such as thermography, creation of multi-spectral images, video laryn- goscopes, cameras, sensor arrays for x-rays, and other highly sensitive arrays for astronomy. While in general digital cameras use a flat sensor, Sony prototyped a curved sensor in 2014 to reduce/eliminate Petzval field curvature that occurs with a flat sensor. Use of a curved sensor allows a shorter and smaller diameter of the lens with reduced elements and components with greater aperture and reduced light fall-off at the edge of the photo.[10] 7.1. IMAGE SENSOR 85

Image sensor on the motherboard of a Nikon Coolpix L2 6 MP

Incoming light

Filter layer

Sensor array

Resulting pattern

Bayer pattern on sensor 86 CHAPTER 7. DAY 7

Full spectrum from outside

Foveon X3 sensor stack (1 pixel)

~ 7µm

Blue absorption Blue sensor

Green absorption Green sensor

~ 5µm

Silicon Wafer Red absorption Red sensor

Foveon’s scheme of vertical filtering for color sensing

Infrared view of the Orion Nebula taken by ESO's HAWK-I, a cryogenic wide-field imager.[9]

7.1.5 Sensors used in digital cameras

7.1.6 Companies

The largest companies that manufacture imaging sensors include the following: 7.1. IMAGE SENSOR 87

• Agilent

• Aptina (formerly division of Micron Technology) - Now part of ON Semiconductor[12]

• Canesta

• Canon

• Dalsa

• Eastman Kodak

• ESS Technology

• Fujifilm

• Panasonic Corporation (formerly Matsushita)

• Mitsubishi

• Nikon

• OmniVision Technologies

• ON Semiconductor (formerly Cypress Semiconductor)[13]

• Samsung

• Sharp

• Sony

• STMicroelectronics

•

• TowerJazz

7.1.7 See also

• Contact image sensor (CIS)

•

• Semiconductor detector

• Full-frame digital SLR

• Image sensor format, the sizes and shapes of common image sensors

• Color filter array, mosaic of tiny color filters over color image sensors

• Sensitometry, the scientific study of light-sensitive materials

• , the development of electronic imaging technology since the 1880s.

• List of large sensor interchangeable-lens video cameras

• Oversampled binary image sensor

• computer vision 88 CHAPTER 7. DAY 7

7.1.8 References

[1] TJ Donegan. “Casio Exilim EX-H50 First Impressions Review”. Retrieved February 23, 2015.

[2] http://cpn.canon-europe.com/content/education/infobank/capturing_the_image/ccd_and_cmos_sensors.do

[3] http://cpn.canon-europe.com/content/education/infobank/capturing_the_image/ccd_and_cmos_sensors.do

[4] Moynihan, Tom. “CMOS Is Winning the Camera Sensor Battle, and Here’s Why”. Retrieved 10 April 2015.

[5] scmos.com, home page

[6] ieee.org - CCD in CMOS Padmakumar R. Rao et al., “CCD structures implemented in standard 0.18 µm CMOS technol- ogy”

[7] semiconductor.net - Sony Backside Illuminated CMOS Image Sensor

[8] nikkeibp.co.jp - OmniVision on Backside-illuminated CMOS Sensors

[9] “Deepest Ever Look into Orion”. Retrieved 13 July 2016.

[10] Steve Dent. “Sony’s first 'curved sensor' photo may herald better images, cheaper lenses”. Retrieved July 8, 2014.

[11] Digicam history 1997

[12] ON Semiconductor to Acquire Aptina Imaging

[13] ON Semiconductor to Acquire Truesense Imaging, Inc

7.1.9 External links

• Digital Camera Sensor Performance Summary by Roger Clark.

7.2 Image sensor format

In digital photography, the image sensor format is the shape and size of the image sensor. The image sensor format of a digital camera determines the angle of view of a particular lens when used with a particular sensor. Because the image sensors in many digital cameras is smaller than the 24 mm × 36 mm image area of full-frame 35 mm cameras, a lens of a given focal will give a narrower field of view on such cameras. The size of a sensor is often expressed as optical format in inches. Other measures are also used; see table of sensor formats and sizes below. Lenses produced for 35 mm film cameras may mount well on the digital bodies, but the larger image circle of the 35 mm system lens allows unwanted light into the camera body, and the smaller size of the image sensor compared to 35 mm film format results in cropping of the image. This latter effect is known as field of view crop. The format size ratio (relative to the 35 mm film format) is known as the field of view crop factor, crop factor, lens factor, focal length conversion factor, focal length multiplier or lens multiplier.

7.2.1 Sensor size and depth of field

Three possible depth of field comparisons between formats are discussed, applying the formulae derived in the article on depth of field. The depths of field of the three cameras may be the same, or different in either order, depending on what is held constant in the comparison. Considering a picture with the same subject distance and angle of view for two different formats:

DOF2 ≈ d1 DOF1 d2 so the DOFs are in inverse proportion to the absolute aperture diameters d1 and d2 . 7.2. IMAGE SENSOR FORMAT 89

Medium format (Kodak KAF 39000 sensor)

35 mm "full frame"

APS-H (Canon) APS-C (Nikon DX, Pentax, Sony) APS-C (Canon) 1" (Sony, Nikon) Foveon (Sigma) Four Thirds 2/3" 1/1.8" 1/2.5"

Comparative dimensions of sensor sizes

Using the same absolute aperture diameter for both formats with the “same picture” criterion (equal angle of view, magnified to same final size) yields the same depth of field. It is equivalent to adjusting the f-number inversely in proportion to crop factor – a smaller f-number for smaller sensors. (This also means that, when holding the shutter speed fixed, the exposure is changed by the adjustment of the f-number required to equalise depth of field. But the aperture area is held constant, so sensors of all sizes receive the same total amount of light energy from the subject. The smaller sensor is then operating at a lower ISO setting, by the square of the crop factor.) And, we might compare the depth of field of sensors receiving the same photometric exposure – the f-number is fixed instead of the aperture diameter – the sensors are operating at the same ISO setting in that case, but the smaller sensor is receiving less total light, by the area ratio. The ratio of depths of field is then

DOF2 ≈ l1 DOF1 l2

where l1 and l2 are the characteristic dimensions of the format, and thus l1/l2 is the relative crop factor between the sensors. It is this result that gives rise to the common opinion that small sensors yield greater depth of field than large ones. An alternative is to consider the depth of field given by the same lens in conjunction with different sized sensors (changing the angle of view). The change in depth of field is brought about by the requirement for a different degree of enlargement to achieve the same final image size. In this case the ratio of depths of field becomes

DOF2 ≈ l2 DOF1 l1 90 CHAPTER 7. DAY 7

7.2.2 Sensor size, noise and dynamic range

Discounting pixel response non-uniformity (PRNU), which is not intrinsically sensor-size dependent, the noises in an image sensor are noise, read noise, and dark noise. The overall signal to noise ratio of a sensor (SNR), observed at the scale of a single pixel, is

PQ t PQ t SNR = √ e = √ e √ √ 2 2 2 2 PQet + Dt + Nr ( PQet) + ( Dt) + Nr where P is the incident photon flux (photons per second in the area of a pixel), Qe is the quantum efficiency, t is the [1] exposure time, D is the pixel dark current in per second and Nr is the pixel read noise in electrons. Each of these noises has a different dependency on sensor size.

Exposure and photon flux

Image sensor noise can be compared across formats for a given fixed photon flux per pixel area (the P in the formulas); this analysis is useful for a fixed number of pixels with pixel area proportional to sensor area, and fixed absolute aperture diameter for a fixed imaging situation in terms of depth of field, diffraction limit at the subject, etc. Or it can be compared for a fixed focal-plane illuminance, corresponding to a fixed f-number, in which case P is proportional to pixel area, independent of sensor area. The formulas above and below can be evaluated for either case.

Shot noise

In the above equation, the SNR is given by

√ PQet √ = PQet PQet

Apart from the quantum efficiency it depends on the incident photon flux and the exposure time,which is equiva- lent to the exposure and the sensor area; since the exposure is the integration time multiplied with the image plane illuminance, and illuminance is the luminous flux per unit area. Thus for equal exposures, the signal to noise ratios of two different size sensors of equal quantum efficiency and pixel count will (for a given final image size) be in propor- tion to the square root of the sensor area (or the linear scale factor of the sensor). If the exposure is constrained by the need to achieve some required depth of field (with the same shutter speed) then the exposures will be in inverse relation to the sensor area, producing the interesting result that if depth of field is a constraint, image shot noise is not dependent on sensor area.

Read noise

The read noise is the total of all the electronic noises in the conversion chain for the pixels in the sensor array. To compare it with photon noise, it must be referred back to its equivalent in photoelectrons, which requires the division of the noise measured in volts by the conversion gain of the pixel. This is given, for an active pixel sensor, by the voltage at the input (gate) of the read divided by the charge which generates that voltage, CG = Vrt/Qrt . This is the inverse of the of the read transistor gate (and the attached floating diffusion) since capacitance [2] C = Q/V . Thus CG = 1/Crt . In general for a planar structure such as a pixel, capacitance is proportional to area, therefore the read noise scales down with sensor area, as long as pixel area scales with sensor area, and that scaling is performed by uniformly scaling the pixel. Considering the signal to noise ratio due to read noise at a given exposure, the signal will scale as the sensor area along with the read noise and therefore read noise SNR will be unaffected by sensor area. In a depth of field constrained situation, the exposure of the larger sensor will be reduced in proportion to the sensor area, and therefore the read noise SNR will reduce likewise. 7.2. IMAGE SENSOR FORMAT 91

Dark noise

Dark current contributes two kinds of noise: dark offset, which is only partly correlated between pixels, and the shot noise associated with dark offset, which is uncorrelated between pixels. Only the shot-noise component Dt is included in the formula above, since the uncorrelated part of the dark offset is hard to predict, and the correlated or mean part is relatively easy to subtract off. The mean dark current contains contributions proportional both to the area and the linear dimension of the photodiode, with the relative proportions and scale factors depending on the design of the photodiode.[3] Thus in general the dark noise of a sensor may be expected to rise as the size of the sensor increases. However, in most sensors the mean pixel dark current at normal temperatures is small, lower than 50 e- per second,[4] thus for typical photographic exposure times dark current and its associated noises may be discounted. At very long exposure times, however, it may be a limiting factor. And even at short or medium exposure times, a few outliers in the dark-current distribution may show up as “hot pixels”.

Dynamic range

Dynamic range is the ratio of the largest and smallest recordable signal, the smallest being typically defined by the 'noise floor'. In the image sensor literature, the noise floor is taken as the readout noise, so DR = Qmax/σreadout [5] [1] (note, the read noise σreadout is the same quantity as Nr referred to in ) The measurement here is made at the level of a pixel (which strictly means that the DR of sensors with different pixel counts is measured over a different spatial , and cannot be compared without normalisation). If we assume sensors with the same pixel count but different sizes, then the pixel area will be in proportion to the sensor area. If the maximum exposure (amount of light per unit area) is the same then both the maximum signal and the read noise reduce in proportion to the pixel (and therefore the sensor) area, so the DR does not change. If the comparison is made according to DOF limited conditions, so that the exposure of the larger sensor is reduced in proportion to the area of the sensor (and pixel, for sensors with equal pixel count) then Qmax is constant, and the read noise ( σreadout ) falls with the sensor area, leading to a higher dynamic range for the smaller sensor. Summarising the above discussion, considering separately the parts of the image signal to noise ratio due to photon shot noise and read noise and their relation to the linear sensor size ratio or 'crop factor' (remembering that conventionally crop factor increases as the sensor gets smaller) then: It should be noted that this discussion isolates the effects of sensor scale on SNR and DR, in reality there are many other factors which affect both these quantities.

7.2.3 Sensor size and diffraction

The resolution of all optical systems is limited by diffraction. One way of considering the effect that diffraction has on cameras using different sized sensors is to consider the modulation transfer function (MTF). Diffraction is one of the factors that contribute to the overall system MTF. Other factors are typically the MTFs of the lens, anti-aliasing filter and sensor sampling window.[6] The spatial cut-off due to diffraction through a lens aperture is

1 ξ = cutoff λN where λ is the wavelength of the light passing through the system and N is the f-number of the lens. If that aperture is circular, as are (approximately) most photographic apertures, then the MTF is given by

{ } 2 [ ]1/2 MTF(ξ/ξ ) = cos−1(ξ/ξ ) − (ξ/ξ ) 1 − (ξ/ξ )2 cutoff π cutoff cutoff cutoff [7] for ξ < ξcutoff and 0 for ξ ≥ ξcutoff The diffraction based factor of the system MTF will therefore scale according to ξcutoff and in turn according to 1/N (for the same light wavelength). In considering the effect of sensor size, and its effect on the final image, the different magnification required to obtain the same size image for viewing must be accounted for, resulting in an additional scale factor of 1/C where C is the relative crop factor, making the overall scale factor 1/(NC) . Considering the three cases above: For the 'same picture' conditions, same angle of view, subject distance and depth of field, then the F-numbers are in the ratio 1/C , so the scale factor for the diffraction MTF is 1, leading to the conclusion that the diffraction MTF at a given depth of field is independent of sensor size. 92 CHAPTER 7. DAY 7

In both the 'same photometric exposure' and 'same lens’ conditions, the F-number is not changed, and thus the spatial cutoff and resultant MTF on the sensor is unchanged, leaving the MTF in the viewed image to be scaled as the magnification, or inversely as the crop factor.

7.2.4 Sensor format and lens size

It might be expected that lenses appropriate for a range of sensor sizes could be produced by simply scaling the same designs in proportion to the crop factor.[8] Such an exercise would in theory produce a lens with the same F-number and angle of view, with a size proportional to the sensor crop factor. In practice, simple scaling of lens designs is not always achievable, due to factors such as the non-scalability of manufacturing tolerance, structural integrity of glass lenses of different sizes and available manufacturing techniques and costs. Moreover, to maintain the same absolute amount of information in an image (which can be measured as the space bandwidth product[9]) the lens for a smaller sensor requires a greater resolving power. The development of the 'Tessar' lens is discussed by Nasse,[10] and shows its transformation from an f/6.3 lens for plate cameras using the original three-group configuration through to an f/2.8 5.2 mm four-element optic with eight extremely aspheric surfaces, economically manufacturable because of its small size. Its performance is 'better than the best 35 mm lenses – but only for a very small image'. In summary, as sensor size reduces, the accompanying lens designs will change, often quite radically, to take advantage of manufacturing techniques made available due to the reduced size. The functionality of such lenses can also take advantage of these, with extreme zoom ranges becoming possible. These lenses are often very large in relation to sensor size, but with a small sensor can be fitted into a compact package. Small body means small lens and means small sensor, so to keep slim and light, the man- ufacturers use a tiny sensor usually less than the 1/2.3” used in most Bridge cameras. At one time only Nokia 808 PureView used a 1/1.2” sensor, almost three times the size of a 1/2.3” sensor. Bigger sensors have the advantage of better image quality, but with improvements in sensor technology, smaller sensors can achieve the feats of earlier larger sensors. These improvements in sensor technology allow smartphone manufacturers to use image sensors as small as 1/4” without sacrificing too much image quality compared to budget point & shoot cameras.[11]

7.2.5 Active area of the sensor

For calculating camera angle of view one should use the size of active area of the sensor. Active area of the sensor implies an area of the sensor on which image is formed in a given mode of the camera. The active area may be smaller than the image sensor, and active area can differ in different modes of operation of the same camera. Active area size depends on the of the sensor and aspect ratio of the output image of the camera. The active area size can depend on number of pixels in given mode of the camera. The active area size and lens focal length determines angles of view.[12]

7.2.6 Sensor size and shading effects

Semiconductor image sensors can suffer from shading effects at large apertures and at the periphery of the image field, due to the geometry of the light cone projected from the exit pupil of the lens to a point, or pixel, on the sensor surface. The effects are discussed in detail by Catrysse and Wandell .[13] In the context of this discussion the most important result from the above is that to ensure a full transfer of light energy between two coupled optical systems such as the lens’ exit pupil to a pixel’s photoreceptor the geometrical extent (also known as etendue or light throughput) of the objective lens / pixel system must be smaller than or equal to the geometrical extent of the microlens / photoreceptor system. The geometrical extent of the objective lens / pixel system is given by

wpixel Gobjective ≃ 2(f/#)objective where wᵢₓₑ is the width of the pixel and (f/#)ₒₑᵢᵥₑ is the f-number of the objective lens. The geometrical extent of the microlens / photoreceptor system is given by

wphotoreceptor Gpixel ≃ 2(f/#)microlens 7.2. IMAGE SENSOR FORMAT 93

where wₒₒᵣₑₑₒᵣ is the width of the photoreceptor and (f/#)ᵢᵣₒₑ is the f-number of the microlens. So to avoid shading,

wphotoreceptor wpixel Gpixel ≥ Gobjective , therefore ≥ (f/#)microlens (f/#)objective

If wₒₒᵣₑₑₒᵣ / wᵢₓₑ = ff, the linear fill factor of the lens, then the condition becomes

≤ × (f/#)microlens (f/#)objective ff Thus if shading is to be avoided the f-number of the microlens must be smaller than the f-number of the taking lens by at least a factor equal to the linear fill factor of the pixel. The f-number of the microlens is determined ultimately by the width of the pixel and its height above the silicon, which determines its focal length. In turn, this is determined by the height of the metallisation layers, also known as the 'stack height'. For a given stack height, the f-number of the microlenses will increase as pixel size reduces, and thus the objective lens f-number at which shading occurs will tend to increase. This effect has been observed in practice, as recorded in the DxOmark article 'F-stop ’[14] In order to maintain pixel counts smaller sensors will tend to have smaller pixels, while at the same time smaller objective lens f-numbers are required to maximise the amount of light projected on the sensor. To combat the effect discussed above, smaller format pixels include engineering design features to allow the reduction in f-number of their microlenses. These may include simplified pixel designs which require less metallisation, 'light pipes’ built within the pixel to bring its apparent surface closer to the microlens and 'back side illumination' in which the wafer is thinned to expose the rear of the and the microlens layer is placed directly on that surface, rather than the front side with its wiring layers. The relative effectiveness of these stratagems is discussed by Aptina in some detail.[15]

7.2.7 Common image sensor formats

Medium-format digital sensors

The largest digital sensors in commercially available cameras are described as medium format, in reference to film formats of similar dimensions. Although the traditional medium format 120 film usually had one side with 6 cm length (the other varying from 4.5 to 24 cm), the most common digital sensor sizes described below are approximately 48 mm × 36 mm (1.9 in × 1.4 in), which is roughly twice the size of a Full-frame digital SLR sensor format. Available CCD sensors include Phase One's P65+ digital back with Dalsa's 53.9 mm × 40.4 mm (2.12 in × 1.59 in) sensor containing 60.5 megapixels[16] and Leica's “S-System” DSLR with a 45 mm × 30 mm (1.8 in × 1.2 in) sensor containing 37-megapixels.[17] In 2010, Pentax released the 40MP 645D medium format DSLR with a 44 mm × 33 mm (1.7 in × 1.3 in) CCD sensor;[18] later models of the 645 series kept the same sensor size but replaced the CCD with a CMOS sensor. In 2016, Hasselblad announced the X1D, a 50MP medium-format mirrorless camera, with a 44 mm × 33 mm (1.7 in × 1.3 in) CMOS sensor.[19] In late 2016, Fujifilm also announced its new Fujifilm GFX 50S medium format, mirrorless entry into the market, with a 43.8 mm × 32.9 mm (1.72 in × 1.30 in) CMOS sensor and 51.4MP. [20] [21]

For interchangeable-lens cameras

Some professional DSLRs, SLTs and MILCs/EVILs use full-frame sensors, equivalent to the size of a frame of 35 mm film. Most consumer-level DSLRs, SLTs and MILCs use relatively large sensors, either somewhat under the size of a frame of APS-C film, with a crop factor of 1.5–1.6; or 30% smaller than that, with a crop factor of 2.0 (this is the Four Thirds System, adopted by Olympus and Panasonic). On September 2011, Nikon announced their new CX format, with a 1” sensor (2.7 crop factor).[22] It has been used in the Nikon 1 camera system (Nikon J1 and V1 models). As of November 2013 there is only one MILC model equipped with a very small sensor, more typical of compact cameras: the Pentax Q7, with a 1/1.7” sensor (4.55 crop factor). See Sensors equipping Compact digital cameras and camera-phones section below. Many different terms are used in marketing to describe DSLR/SLT/MILC sensor formats, including the following: 94 CHAPTER 7. DAY 7

35 mm “full frame” 36×24 mm 864 mm²

APS-H (Canon) APS-C (Nikon, Sony, APS-C (Canon) 28.7×19 mm Pentax, Fuji etc.) 22.2×14.8 mm 548 mm² ≈23.6×15.7 mm 329 mm² ≈370 mm²

Foveon (Sigma) Four Thirds System 1″ (Nikon,Sony) 20.7×13.8 mm (Olympus, Panasonic) 13.2×8.8 mm 286 mm² 17.3×13 mm 116 mm² 225 mm²

2/3″ (Fuji, Nokia) 1/1.7″ 1/2.5″ 8.6×6.6 mm 7.6×5.7 mm 5.76×4.29 mm 58.1 mm² 43 mm² 25 mm²

Sizes of sensors used in most current digital cameras relative to a standard 35mm frame.

• 860 mm² area Full-frame digital SLR format, with sensor dimensions nearly equal to those of 35 mm film (36×24 mm)

• 370 mm² area APS-C standard format from Nikon, Pentax, Sony, Fujifilm, Sigma (crop factor 1.5) (Actual APS-C film is bigger, however.) 7.2. IMAGE SENSOR FORMAT 95

• 330 mm² area APS-C smaller format from Canon (crop factor 1.6) • 225 mm² area Micro Four Thirds System format from Panasonic, Olympus, Black Magic and Polaroid (crop factor 2.0) • 116 mm² area 1” Nikon CX format used in Nikon 1 series and Samsung mini-NX series (crop factor 2.7) • 43 mm² area 1/1.7” Pentax Q7 (4.55 crop factor)

Obsolescent and out-of-production sensor sizes include:

• 548 mm² area Leica's M8 and M8.2 sensor (crop factor 1.33). Current M-series sensors are effectively full-frame (crop factor 1.0). • 548 mm² area Canon's APS-H format for high-speed pro-level DSLRs (crop factor 1.3). Current 1D/5D-series sensors are effectively full-frame (crop factor 1.0). • 370 mm² area APS-C crop factor 1.5 format from Epson, Samsung NX, Konica Minolta. • 286 mm² area Foveon X3 format used in Sigma SD-series DSLRs and DP-series mirrorless (crop factor 1.7). Later models such as the SD1, DP2 Merrill and the Quattro-series use a crop factor 1.5 Foveon sensor. • 225 mm² area Four Thirds System format from Olympus (crop factor 2.0) • 30 mm² area 1/2.3” original Pentax Q (5.6 crop factor). Current Q-series cameras have a crop factor of 4.55.

When full-frame sensors were first introduced, production costs could exceed twenty times the cost of an APS-C sensor. Only twenty full-frame sensors can be produced on an 8 inches (20 cm) silicon wafer, which would fit 100 or more APS-C sensors, and there is a significant reduction in yield due to the large area for contaminants per component. Additionally, full frame sensor fabrication originally required three separate exposures during the stage, which requires separate masks and quality control steps. Canon selected the intermediate APS-H size, since it was at the time the largest that could be patterned with a single mask, helping to control production costs and manage yields.[23] Newer photolithography equipment now allows single-pass exposures for full-frame sensors, although other size-related production constraints remain much the same. Due to the ever-changing constraints of semiconductor fabrication and processing, and because camera manufacturers often source sensors from third-party foundries, it is common for sensor dimensions to vary slightly within the same nominal format. For example, the Nikon D3 and D700 cameras’ nominally full-frame sensors actually measure 36 × 23.9 mm, slightly smaller than a 36 × 24 mm frame of 35 mm film. As another example, the 's sensor (made by Sony) measures 23.5 × 15.7 mm, while the contemporaneous K20D's sensor (made by Samsung) measures 23.4 × 15.6 mm. Most of these image sensor formats approximate the 3:2 aspect ratio of 35 mm film. Again, the Four Thirds System is a notable exception, with an aspect ratio of 4:3 as seen in most compact digital cameras (see below). Nowadays, image quality of some Micro Four Thirds system cameras can be compared with APS-C cameras and even better than some of them. Due to the smaller sensor size, the m4/3 cameras still can’t compete with full frame and some APS-C cameras in High-ISO.[24]

Smaller sensors

Most sensors are made for camera phones, compact digital cameras, and bridge cameras. Most image sensors equip- ping compact cameras have an aspect ratio of 4:3. This matches the aspect ratio of the popular SVGA, XGA, and SXGA display resolutions at the time of the first digital cameras, allowing images to be displayed on usual monitors without cropping. As of December 2010 most compact digital cameras used small 1/2.3” sensors. Such cameras include Canon Power- shot SX230 IS, Fuji Finepix Z90 and Nikon Coolpix S9100. Some older digital cameras (mostly from 2005–2010) used even smaller 1/2.5” sensors: these include Panasonic Lumix DMC-FS62, Canon Powershot SX120 IS, Sony Cyber-shot DSC-S700, and Casio Exilim EX-Z80. High-end compact cameras using sensors of nearly twice the area of those equipping common compacts include Canon PowerShot G12 (1/1.7”) and Powershot S90/S95 (1/1.7”), Ricoh GR Digital IV (1/1.7”), Nikon Coolpix P7100 96 CHAPTER 7. DAY 7

(1/1.7”), Samsung EX1 (1/1.7”), Panasonic DMC-LX5 (1/1.63”) and LX7 (1/1.7”) and Olympus XZ-1(1/1.63”). Fujifilm FinePix X-10 (and subsequent high-end compact Fuji models) had a considerably larger, 2/3” sensor. Then, in 2012, Sony introduced DSC-RX100, a real compact (weight 213 grams (7.5 oz)) equipped with a relatively large 1” sensor. Canon also labels its PowerShot G1 X (equipped with a 1.5” sensor, larger than the 4/3” sensors on some compact DSLRs) as a “compact camera"; however, at 534 grams (18.8 oz) it is arguably a rather than a compact.

Camera sensor area (log scale) 10000

1000

100 Area in mm^2

10

1 Full 1/4" 1/6" Leaf P65+ Leica 1/1.7" 1/1.8" 1/2.5" 1/3.6" APS-H APS-C KAF-39000 Four-Thirds

For many years until Sep. 2011 a gap existed between compact digital and DSLR camera sensor sizes. The x axis is a discrete set of sensor format sizes used in digital cameras, not a linear measurement axis.

Finally, Sony has the DSC-RX1 and DSC-RX1R cameras in their lineup, which have a full-frame sensor usually only used in professional DSLRs, SLTs and MILCs. Due to the constraints of powerful zoom objectives , most current bridge cameras have 1/2.3” sensors, as small as those used in common more compact cameras. In 2011 the high-end Fuji XS-1 was equipped with a much larger 2/3” sensor. In 2013-2014, both Sony (Cyber-shot DSC-RX10) and Panasonic (Lumix DMC-FZ1000) produced bridge cameras with 1” sensors. The sensors of camera phones are typically much smaller than those of typical compact cameras, allowing greater miniaturization of the electrical and optical components. Sensor sizes of around 1/6” are common in camera phones, and digital camcorders. The Nokia N8's 1/1.83” sensor was the largest in a phone in late 2011. The Nokia 808 surpasses compact cameras with its 41 million pixels, 1/1.2” sensor.[25]

Table of sensor formats and sizes

Sensor sizes are expressed in inches notation because at the time of the popularization of digital image sensors they were used to replace video camera tubes. The common 1” circular video camera tubes had a rectangular photo sensitive area about 16mm diagonal, so a digital sensor with a 16 mm diagonal size was a 1” video tube equivalent. The name of a 1” digital sensor should more accurately be read as “one inch video camera tube equivalent” sensor. 7.2. IMAGE SENSOR FORMAT 97

Current digital image sensor size descriptors are the video camera tube equivalency size, not the actual size of the sensor. For example, a 1” sensor has a diagonal measurement of 16mm.[26][27] Sizes are often expressed as a fraction of an inch, with a one in the numerator, and a decimal number in the denomi- nator. For example, 1/2.5 converts to 2/5 as a simple fraction, or 0.4 as a decimal number. This “inch” system brings a result approximately 1.5 times the length of the diagonal of the sensor. This "optical format" measure goes back to the way image sizes of video cameras used until the late 1980s were expressed, referring to the outside diameter of the glass envelope of the video camera tube. David Pogue of The New York Times states that “the actual sensor size is much smaller than what the camera companies publish – about one-third smaller.” For example, a camera advertis- ing a 1/2.7” sensor does not have a sensor with a diagonal of 0.37"; instead, the diagonal is closer to 0.26”.[28][29][30] Instead of “formats”, these sensor sizes are often called types, as in “1/2-inch-type CCD.” Due to inch-based sensor formats being not standardized, their exact dimensions may vary, but those listed are typical.[29] The listed sensor areas span more than a factor of 1000 and are proportional to the maximum possible collection of light and image resolution (same , i.e., minimum F-number), but in practice are not directly proportional to or resolution due to other limitations. See comparisons.[31][32] Film format sizes are included for comparison.

7.2.8 See also

• Full-frame digital SLR

• Sensor size and angle of view

• 35 mm equivalent focal length

• Film format

• Digital versus film photography

• List of large sensor interchangeable-lens video cameras

• Angle of view

• Crop factor

•

7.2.9 Notes and references

[1] Fellers, Thomas J.; Davidson, Michael W. “CCD Noise Sources and Signal-to-Noise Ratio”. Hamamatsu Corporation. Retrieved 20 November 2013.

[2] Aptina Imaging Corporation. “Leveraging Dynamic Response Pixel Technology to Optimize Inter-scene Dynamic Range” (PDF). Aptina Imaging Corporation. Retrieved 17 December 2011.

[3] Loukianova, Natalia V.; Folkerts, Hein Otto; Maas, Joris P. V.; Verbugt, Joris P. V.; Daniël W. E. Mierop, Adri J.; Hoekstra, Willem; Roks, Edwin and Theuwissen, Albert J. P. (January 2003). “Leakage Current Modeling of Test Structures for Characterization of Dark Current in CMOS Image Sensors” (PDF). IEEE Transactions on Electron Devices. 50 (1): 77–83. doi:10.1109/TED.2002.807249. Retrieved 17 December 2011.

[4] “Dark Count”. Apogee Imaging Systems. Retrieved 17 December 2011.

[5] Kavusi, Sam; El Gamal, Abbas (2004). “Quantitative Study of High Dynamic Range Image Sensor Architectures” (PDF). Proc. of SPIE-IS&T Electronic Imaging. 5301: 264–275. Retrieved 17 December 2011.

[6] Osuna, Rubén; García, Efraín. “Do Sensors “Outresolve” Lenses?". The Luminous Landscape. Retrieved 21 December 2011.

[7] Boreman, Glenn D. (2001). Modulation Transfer Function in Optical and Electro-Optical Systems. SPIE Press. p. 120. ISBN 978-0-8194-4143-0.

[8] Ozaktas, Haldun M; Urey, Hakan; Lohmann, Adolf W. (1994). “Scaling of diffractive and refractive lenses for optical computing and interconnections”. Applied Optics. 33 (17): 3782–3789. doi:10.1364/AO.33.003782. 98 CHAPTER 7. DAY 7

[9] Goodman, Joseph W (2005). Introduction to Fourier optics, 3rd edition. Greenwood Village, CO: Roberts and Company. p. 26. ISBN 0-9747077-2-4. [10] Nasse, H. H. “From the Series of Articles on Lens Names: Tessar” (PDF). Carl Zeiss AG. Retrieved 19 December 2011. [11] Simon Crisp. “Camera sensor size: Why does it matter and exactly how big are they?". Retrieved January 29, 2014. [12] Stanislav Utochkin. “Specifying active area size of the image sensor”. Retrieved May 21, 2015. [13] Catrysse, Peter B.; Wandell, Brian A. (2005). “Roadmap for CMOS image sensors: Moore meets Planck and Sommerfeld” (PDF). Proceedings of the International Society for Optical Engineering. 5678 (1). doi:10.1117/12.592483. Retrieved 29 January 2012. [14] DxOmark. “F-stop blues”. DxOMark Insights. Retrieved 29 January 2012. [15] Aptina Imaging Corporation. “An Objective Look at FSI and BSI” (PDF). Aptina Technology White Paper. Retrieved 29 January 2012. [16] “The Phase One P+ Product Range”. PHASE ONE. Retrieved 2010-06-07. [17] “ with 56% larger sensor than full frame” (Press release). Leica. 2008-09-23. Retrieved 2010-06-07. [18] “Pentax unveils 40MP 645D medium format DSLR” (Press release). Pentax. 2010-03-10. Retrieved 2010-12-21. [19] Johnson, Allison (2016-06-22). “Medium-format mirrorless: Hasselblad unveils X1D”. Digital Photography Review. Retrieved 2016-06-26. [20] “Fujifilm announces development of new medium format “GFX” mirroless camera system” (Press release). Fujifilm. 2016- 09-19. [21] “Fujifilm’s Medium Format GFX 50S to Ship in February for $6,500”. 2017-01-19. [22] “Nikon unveils J1 small sensor mirrorless camera as part of Nikon 1 system”, Digital Photography Review. [23] “Canon’s Full Frame CMOS Sensors” (PDF) (Press release). 2006. Retrieved 2013-05-02. [24] Stefe Huff (February 18, 2015). “The Olympus OM-D E-M5 Mark II Review. Olympus continues to innovate”. Retrieved March 6, 2015. [25] http://europe.nokia.com/PRODUCT_METADATA_0/Products/Phones/8000-series/808/Nokia808PureView_Whitepaper. pdf Nokia PureView imaging technology whitepaper [26] Staff (7 October 2002). “Making (some) sense out of sensor sizes”. Digital Photography Review. Digital Photography Review. Retrieved 29 June 2012. [27] Staff. “Image Sensor Format”. Imaging Glossary Terms and Definitions. SPOT IMAGING SOLUTIONS. Retrieved 3 June 2015. [28] Pogue, David (2010-12-22). “Small Cameras With Big Sensors, and How to Compare Them”. The New York Times. [29] Bockaert, Vincent. “Sensor Sizes: Camera System: Glossary: Learn”. Digital Photography Review. Retrieved 2012-04- 09. [30] [31] Camera Sensor Ratings DxOMark [32] Imaging-resource: Sample images Comparometer Imaging-resource [33] Defined here as the ratio of the diagonal of a full 35 frame to that of the sensor format, that is CF=diag₃₅ / diagₑₒᵣ. [34] “Unravelling Sensor Sizes - Photo Review”. www.photoreview.com.au. Retrieved 2016-09-22. [35] – Full phone specifications, GSMArena.com, February 25, 2013, retrieved 2013-09-21 [36] Camera sensor size: Why does it matter and exactly how big are they?, Gizmag, March 21, 2013, retrieved 2013-06-19 [37] Comparison of iPhone Specs, PhoneArena [38] “Diagonal 7.87mm (Type 1/2.3) 20.7M Pixel CMOS Image Sensor with Square Pixel for Color Cameras” (PDF). Sony. Retrieved 21 October 2014. [39] KODAK KAF-39000 IMAGE SENSOR, DEVICE PERFORMANCE SPECIFICATION (PDF), KODAK, April 30, 2010, re- trieved 2014-02-09 [40] Hasselblad H5D-60 medium-format DSLR camera, B&H PHOTO VIDEO, retrieved 2013-06-19 7.2. IMAGE SENSOR FORMAT 99

7.2.10 External links

• : Photons to Bits and Beyond: The Science & Technology of Digital, Oct. 13, 2011 (YouTube Video of lecture)

• Joseph James: Equivalence at Joseph James Photography • Simon Tindemans: Alternative photographic parameters: a format-independent approach at 21stcenturyshoe- box • Compact Camera High ISO modes: Separating the facts from the hype at dpreview.com, May 2007

• The best compromise for a compact camera is a sensor with 6 million pixels or better a sensor with a pixel size of >3µm at 6mpixel.org Chapter 8

Day 8

8.1 Full-frame digital SLR

The term full frame is used by users of digital single-lens reflex cameras (DSLRs) as a shorthand for an image sensor format which is the same size as 35mm format (36 mm × 24 mm) film.[1][2] Historically, 35mm was considered a small film format compared with medium format, large format and even larger. This is in contrast to cameras with smaller sensors (for instance, those with a size equivalent to APS-C-size film), much smaller than a full 35mm frame. Currently, the majority of digital cameras, both compact and SLR models, use a smaller-than-35 mm frame, as it is easier and cheaper to manufacture imaging sensors at a smaller size. Historically, the earliest digital SLR models, such as the Nikon NASA F4 or Kodak DCS 100, also used a smaller sensor. Kodak states that 35mm film has the equivalent of 6,000 pixel horizontal resolution according to a Senior Vice President of IMAX.[3]

8.1.1 Use of 35mm film-camera lenses

If the lens mounts are compatible, many lenses, including manual-focus models, designed for 35mm cameras can be mounted on DSLR cameras. When a lens designed for a full-frame camera, whether film or digital, is mounted on a DSLR with a smaller sensor size, only the center of the lens’ image circle is captured. The edges are cropped off, which is equivalent to zooming in on the center section of the imaging area. The ratio of the size of the full-frame 35mm format to the size of the smaller format is known as the "crop factor" or “focal-length multiplier”, and is typically in the range 1.3–2.0 for non-full-frame digital SLRs.

8.1.2 Advantages and disadvantages of full-frame digital SLRs

35mm lenses

When used with lenses designed for full frame film or digital cameras full-frame DSLRs offer a number of advantages compared to their smaller-sensor counterparts. One advantage is that wide-angle lenses designed for full-frame 35mm retain that same wide angle of view. On smaller-sensor DSLRs, wide-angle lenses have smaller angles of view equivalent to those of longer-focal-length lenses on 35mm film cameras. For example, a 24 mm lens on a camera with a crop factor of 1.5 has a 62° diagonal angle of view, the same as that of a 36 mm lens on a 35mm film camera. On a full-frame digital camera, the 24 mm lens has the same 84° angle of view as it would on a 35mm film camera. If the same lens is used on both full-frame and cropped formats, and the subject distance is adjusted to have the same field of view (i.e., the same framing of the subject) in each format, depth of field (DoF) is in inverse proportion to the format sizes, so for the same f-number, the full-frame format will have less DoF. Equivalently, for the same DoF, the full-frame format will require a larger f-number (that is, a smaller aperture diameter). This relationship is approximate and holds for moderate subject distances, breaking down as the distance with the smaller format approaches the , and as the magnification with the larger format approaches the macro range. There are optical quality implications as well—not only because the image from the lens is effectively cropped—but because many lens designs are now optimized for sensors smaller than 36 mm × 24 mm. The rear element of any SLR lens must have clearance for the camera’s reflex mirror to move up when the shutter is released; with a wide-

100 8.1. FULL-FRAME DIGITAL SLR 101

35 mm “full frame” 36×24 mm 864 mm²

APS-H (Canon) APS-C (Nikon, Sony, APS-C (Canon) 28.7×19 mm Pentax, Fuji etc.) 22.2×14.8 mm 548 mm² ≈23.6×15.7 mm 329 mm² ≈370 mm²

Foveon (Sigma) Four Thirds System 1″ (Nikon,Sony) 20.7×13.8 mm (Olympus, Panasonic) 13.2×8.8 mm 286 mm² 17.3×13 mm 116 mm² 225 mm²

2/3″ (Fuji, Nokia) 1/1.7″ 1/2.5″ 8.6×6.6 mm 7.6×5.7 mm 5.76×4.29 mm 58.1 mm² 43 mm² 25 mm²

The sizes of sensors used in most current digital cameras, relative to a 35mm format

angle lens, this requires a retrofocus design, which is generally of inferior optical quality.[4] Because a cropped-format sensor can have a smaller mirror, less clearance is needed, and some lenses, such as the EF-S lenses for the Canon APS-C sized bodies,[5] are designed with a shorter back-focus distance; however, they cannot be used on bodies with larger sensors. 102 CHAPTER 8. DAY 8

An APS-C format DSLR (left) and a full-frame DSLR (right) show the difference in the size of the sensors.

The full-frame sensor can also be useful with wide-angle perspective control or tilt/shift lenses; in particular, the wider angle of view is often more suitable for architectural photography. While full-frame DSLRs offer advantages for wide-angle photography, smaller-sensor DSLRs offer some advantages for telephoto photography because the smaller angle of view of small-sensor DSLRs enhances the telephoto effect of the lenses. For example, a 200 mm lens on a camera with a crop factor of 1.5× has the same angle of view as a 300 mm lens on a full-frame camera. The extra “reach”, for a given number of pixels, can be helpful in specific areas of photography such as wildlife or sports.[6] Lower size sensors also allow for the use of a wider range of lenses, since some types of optical impurities (specifically vignetting) are most visible around the edge of the lens. By only using the center of the lens, these impurities are not noticed. In practice, this allows for the use of lower cost glass without corresponding loss of quality.[7] Finally, full frame sensors allow for sensor designs that result in lower noise levels at high ISO and a greater dynamic range in captured images. Pixel density is lower on full frame sensors. This means the pixels can be either spaced further apart from each other, or each photodiode can be manufactured at a slightly larger size. Larger pixel sizes can capture more light which has the advantage of allowing more light to be captured before over saturation of the photodiode. Additionally, less noise is generated by adjacent pixels and their emf fields with larger or greater spacing between photodiodes. For a given number of pixels, the larger sensor allows for larger pixels or photosites that provide wider dynamic range and lower noise at high ISO levels.[8] As a consequence, full-frame DSLRs may produce better quality images in certain high contrast or low light situations. Production costs for a full-frame sensor can exceed twenty times the costs for an APS-C sensor. Only 20 full- frame sensors will fit on an 8-inch (200 mm) silicon wafer, and yield is comparatively low because the sensor’s large area makes it very vulnerable to contaminants—20 evenly distributed defects could theoretically ruin an entire wafer. Additionally, when full-frame sensors were first produced, they required three separate exposures during the photolithography stage, tripling the number of masks and exposure processes.[9] Modern photolithography equipment now allows single-pass exposures for full-frame sensors, but other size-related production constraints remain much the same. Some full-frame DSLRs intended mainly for professional use include more features than typical consumer-grade DSLRs, so some of their larger dimensions and increased mass result from more rugged construction and additional features as opposed to this being an inherent consequence of the full-frame sensor.

8.1.3 Past and present full-frame digital cameras

DSLRs

• Canon EOS 5D (2005)

• Canon EOS 5D Mark II (2008) 8.1. FULL-FRAME DIGITAL SLR 103

Nikkor 24 mm PC-E tilt-shift lens on full-frame DSLR camera

• Canon EOS 5D Mark III (2 March 2012)

• Canon EOS 5Ds / 5Ds R (February 6, 2015)

• Canon EOS 5D Mark IV (August 2016)

• Canon EOS 6D (17 September 2012)[10]

• Canon EOS-1D X Mark II (February 2, 2016)

• Canon EOS-1D X (2012)[11]

• Canon EOS-1Ds Mark III (2007)

• Canon EOS-1Ds Mark II (2004)

• Canon EOS-1Ds (2002)

• Contax N Digital (2002)

• Kodak DCS Pro 14n (2003)

• Kodak DCS Pro SLR/c (2004)

• Kodak DCS Pro SLR/n (2004)

• Nikon D3 (2007)

• (2009)[12]

• (2008)[13]

• (2012)[14]

• (February 24, 2014)

• (January 6, 2016) 104 CHAPTER 8. DAY 8

• (8 October 2013)[15]

• Nikon D600 (13 September 2012)[16]

• Nikon D700 (2008)

• (September 12, 2014)

• [17] / Nikon D800E (2012)

• (June 26, 2014)

• (5 November 2013)[18]

• Pentax K-1 (February 18, 2016)

• Sony α DSLR-A850 (2009)[19]

• Sony α DSLR-A900 (2008)

• Sony α SLT-A99 / Sony α SLT-A99V (12 September 2012)[20] (utilizing a semi-transparent SLT mirror)

• Sony α ILCA-99M2 (2016)

The Nikon E2/E2s (1994),[21] E2N/E2NS (1996)[22] and E3/E3S (1998)[23] digital SLRs as well as the similar Fujifilm Fujix DS-505/DS-515, DS-505A/DS-515A and DS-560/DS-565 models used a reduction optical system (ROS) to compress a full-frame 35mm field onto a smaller 2/3-inch (11 mm diagonal) CCD imager. They were therefore not digital SLRs with full-frame sensors, however had an angle of view equivalent to full-frame digital SLRs for a given lens; they had no crop factor with respect to angle of view.[24] Nikon has designated its full frame cameras as FX format and its smaller sensor cameras as the DX format.

Rangefinders

• Leica M9[25] (2009)

• Leica M9-P[25] (2011)

• Monochrom (2012)[26]

• Leica M-E (17 September 2012)

• Leica M (17 September 2012)

Other technologies

• Sony Handycam NEX-VG900 (announced September 2012) – a 35mm full-frame video camera (also capable to shoot hi-resolution photos) with interchangeable lenses (Sony E-mount)

• Sony Cyber-shot DSC-RX1 (announced September 2012) and Sony Cyber-shot DSC-RX1R (announced June 2013) – full-frame compact cameras with fixed lens

• The Sony α7 series (first models announced in October 2013, with upgrades to the present) – full-frame mirrorless interchangeable-lens cameras (Sony E-mount; full-frame coverage available with lenses designated as “FE”)

• Leica SL (announced October 2015) – full-frame mirrorless interchangeable-lens camera (Leica L-mount)

8.1.4 Features of some full frame DSLR cameras

[27] 8.1. FULL-FRAME DIGITAL SLR 105

8.1.5 Prototype full-frame digital SLRs

• Pentax MZ-D “MR-52” (presented in 2000, based on Pentax MZ-S, with the same sensor as Contax N, it never went into production)[28] • Sony Alpha flagship model “CX62500” (presented at PMA 2007, early prototype of what one-and-a-half years later became the DSLR-A900 (aka “CX85100”), though with many detail differences)[29][30]

8.1.6 See also

• Image sensor format

8.1.7 References

[1] Nigel Atherton; Steve Crabb; Tim Shelbourne (2006). An Illustrated A to Z of Digital Photography: People And Portraits. Sterling Publishing Co. Inc. ISBN 2-88479-087-X.

[2] Ross Hoddinott (2006). Digital Macro Photography. Sterling Publishing Co. Inc. ISBN 1-86108-452-8.

[3] "/Film Interview: IMAX Executives Talk 'The Hunger Games: Catching Fire' and IMAX Misconceptions”. Slash Film. December 2, 2013. Retrieved December 17, 2013.

[4] “Retrofocus Design Problems: A Synopsis”. Camerarepair.com. Retrieved 2010-12-30.

[5] “The Canon Camera Story: 2001-2004”. November 2004. Retrieved 2009-09-26.

[6] Barbara Gerlach (2007). Digital : The Art and the Science. Focal Press. p. 67. ISBN 978-0-240- 80856-7.

[7] Bourne, Scott. “Seven Myths About the Need for Full Frames”. Retrieved 15 October 2013.

[8] “Full-frame sensors”. Photocrati. Retrieved 2010-12-30.

[9] “Canon’s Full-Frame CMOS Sensors: The Finest Tools for Digital Photography” (PDF) (Press release). Canon. 2006. Archived from the original (PDF) on 2010-10-10. Retrieved 2009-12-26.

[10] “Canon Announces Its Smallest and Lightest Full-Frame Digital SLR Camera For Serious Photographers” (Press release). Canon U.S.A., Inc. September 17, 2012. Retrieved September 17, 2012.

[11] “Canon U.S.A. Introduces The New Canon EOS-1D X Digital SLR Camera, Re-Designed From The Inside Out” (Press release). Canon U.S.A. October 18, 2011. Retrieved October 18, 2011.

[12] “Nikon D3s press announcement as of October 14th, 2009”. Press.nikonusa.com. 2009-10-14. Retrieved 2010-12-30.

[13] “Nikon D3x press announcement as of November 30th, 2008”. Press.nikonusa.com. 2008-11-30. Retrieved 2010-12-30.

[14] “When There Is No Second Chance: The New Nikon FX-Format D4 Multi-Media Digital SLR is The Definitive Unification Of Speed And Precision” (Press release). Nikon Inc. January 5, 2012. Retrieved January 6, 2012.

[15] “Concentrate on the Clarity: The New Nikon D610 FX-Format D-SLR Places Emphasis on the Image Making Experience” (Press release). Nikon Inc. October 8, 2013. Retrieved October 8, 2013.

[16] “Performance that Fuels the Passion: The New Nikon D600 Puts FX-Format in Focus for Photo Enthusiasts” (Press release). Nikon Inc. September 13, 2012. Retrieved September 13, 2012.

[17] “Expectations Surpassed: The 36.3-Megapixel Nikon D800 Is The HD-SLR That Shatters Conventional Res- olution Barriers For Maximum Fidelity” (Press release). Nikon Inc. February 6, 2012. Retrieved February 7, 2012.

[18] “Fall in Love Again: New Df D-SLR is Undeniably a Nikon with Legendary Performance and Timeless Design” (Press release). Nikon Inc. November 4, 2013. Retrieved November 5, 2013.

[19] “Sony α DSLR-A850 press announcement as of August 27th, 2009”. News.sel.sony.com. 2009-08-27. Retrieved 2010- 12-30.

[20] “Sony introduces full-frame α99” (Press release). Sony. September 12, 2012. Retrieved September 17, 2012.

[21] “Technical information on Nikon E2/E2s and Fujifilm Fujix DS-505/DS-515 at MIR - Photography in Malaysia”. Mir.com.my. Retrieved 2010-12-30. 106 CHAPTER 8. DAY 8

[22] “Technical information on Nikon E2N/E2Ns and Fujifilm Fujix DS-505A/DS-515A at MIR - Photography in Malaysia”. Mir.com.my. Retrieved 2010-12-30.

[23] “Technical information on Nikon E3/E3s and Fujifilm Fujix DS-560/DS-565 at MIR - Photography in Malaysia”. Mir.com.my. Retrieved 2010-12-30.

[24] Jarle Aasland, Nikon E2N, NikonWeb.com.

[25] Leica M9, Leica Camera AG

[26] “Leica announces M-Monochrom black-and-white 18MP rangefinder”. Digital Photography Review. May 10, 2012. Re- trieved June 17, 2012.

[27] http://www.gizmag.com/full-frame-dslr-comparison-guide/28114/

[28] Asahi Optical Historical Club (2001) “MR-52” 6 Megapixel digital SLR

[29] – Charlie White (2007-03-08). “Charlie White’s PMA March 8th, 2007 report on Sony press announcement in regard to Sony Alpha flagship model “CX62500"". Gizmodo.com. Retrieved 2010-12-30.

[30] Matthias Paul, Sony Alpha CX model codes overview Forum article in German Minolta-Forum as of September 30th, 2009 Chapter 9

Day 9

9.1 Digital single-lens reflex camera

A digital single-lens reflex camera (also called a digital SLR or DSLR) is a digital camera that combines the optics and the mechanisms of a single-lens reflex camera with a digital imaging sensor, as opposed to photographic film. The reflex design scheme is the primary difference between a DSLR and other digital cameras. In the reflex design, light travels through the lens, then to a mirror that alternates to send the image to either the viewfinder or the image sensor. The alternative would be to have a viewfinder with its own lens, hence the term “single lens” for this design. By using only one lens, the viewfinder of a DSLR presents an image that will not perceptibly differ from what is captured by the camera’s sensor. DSLRs largely replaced film-based SLRs during the 2000s, and despite the rising popularity of mirrorless system cameras in the early 2010s, DSLRs remained the most common type of interchangeable lens camera in use as of 2014.

9.1.1 Design of DSLR cameras

Like SLRs DSLRs typically use interchangeable lenses (1) with a proprietary lens mount. A movable mechanical mirror system (2) is switched down (exact 45-degree angle) to direct light from the lens over a matte focusing screen (5) via a condenser lens (6) and a pentaprism/pentamirror (7) to an optical viewfinder eyepiece (8). Most of the entry-level DSLRs use a pentamirror instead of the traditional pentaprism. Focusing can be manual or automatic, activated by pressing half-way on the shutter release or a dedicated AF button. To take an image, the mirror swings upwards in the direction of the arrow, the focal-plane shutter (3) opens, and the image is projected and captured on the image sensor (4), after which actions, the shutter closes, the mirror returns to the 45-degree angle, and the built in drive mechanism re-tensions the shutter for the next exposure. Compared to the newer concept of mirrorless interchangeable-lens cameras this mirror/prism system is the charac- teristic difference providing direct, accurate optical preview with separate autofocus and exposure metering sensors. Essential parts of all digital cameras are some electronics like amplifier, analog to digital converter, image and other (micro-)processors for processing the digital image, performing data storage and/or driving an electronic display.

Phase-detection autofocus

Main article: Phase detection autofocus

DSLRs typically use autofocus based on phase detection. This method allows the optimal lens position to be cal- culated, rather than “found”, as would be the case with autofocus based on contrast maximisation. Phase-detection autofocus is typically faster than other passive techniques. As the phase sensor requires the same light going to the im- age sensor, it was previously only possible with an SLR design. However, with the introduction of focal-plane phase detect autofocusing in mirrorless interchangeable lens cameras by Sony, Fuji, Olympus and Panasonic, cameras can

107 108 CHAPTER 9. DAY 9

7 8

6 5

1 2 3 4

The photographer can see the subject before taking an image by the mirror. When taking an image the mirror will swing up and light will go to the sensor instead.

1. Camera lens 2. Reflex mirror 3. Focal-plane shutter 4. Image sensor 5. Matte focusing screen 6. Condenser lens 7. Pentaprism/pentamirror 8. Viewfinder eyepiece now employ both phase detect and contrast detect AF points concurrently with higher content awareness.

9.1.2 Features commonly seen in DSLR designs

1 2 3 4 7 8 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 109

Cutaway of an Olympus E-30 DSLR (key: see above)

Mode dial

Digital SLR cameras, along with most other digital cameras, generally have a mode dial to access standard camera settings or automatic scene-mode settings. Sometimes called a “PASM” dial, they typically provide modes such as program, aperture-priority, shutter-priority, and full manual modes. Scene modes vary from camera to camera, and these modes are inherently less customizable. They often include landscape, portrait, action, macro, night, and silhouette, among others. However, these different settings and shooting styles that “scene” mode provides can be achieved by calibrating certain settings on the camera. Professional DSLRs seldom contain automatic scene modes as professionals often do not require these and professionals know how to achieve the looks they want.[1]

Dust reduction systems

Main article: Dust reduction system

A method to prevent dust entering the chamber, by using a “dust cover” filter right behind the lens mount, was used by Sigma in its first DSLR, the Sigma SD9, in 2002. Olympus used a built-in sensor cleaning mechanism in its first DSLR that had a sensor exposed to air, the Olympus E-1, in 2003 (all previous models each had a non-interchangeable lens, preventing direct exposure of the sensor to outside environmental conditions). Several Canon DSLR cameras rely on dust reduction systems based on vibrating the sensor at ultrasonic to remove dust from the sensor.[2]

Interchangeable lenses

Main articles: Photographic lens and Lenses for SLR and DSLR cameras The ability to exchange lenses, to select the best lens for the current photographic need, and to allow the attachment 110 CHAPTER 9. DAY 9

Canon EF-S 18-135mm APS-C Zoom lens of specialised lenses, is one of the key factors in the popularity of DSLR cameras, although this feature is not unique to the DSLR design and mirrorless interchangeable lens cameras are becoming increasingly popular. Interchangeable lenses for SLRs and DSLRs (also known as “Glass”) are built to operate correctly with a specific lens mount that is generally unique to each brand. A photographer will often use lenses made by the same manufacturer as the camera body (for example, Canon EF lenses on a Canon body) although there are also many independent lens manufacturers, such as Sigma, , Tokina, and Vivitar that make lenses for a variety of different lens mounts. There are also lens adapters that allow a lens for one lens mount to be used on a camera body with a different lens mount but with often reduced functionality. Many lenses are mountable, “diaphragm-and-meter-compatible”, on modern DSLRs and on older film SLRs that use the same lens mount. However, when lenses designed for 35 mm film or equivalently sized digital image sensors are used on DSLRs with smaller sized sensors, the image is effectively cropped and the lens appears to have a longer focal length than its stated focal length. Most DSLR manufacturers have introduced lines of lenses with image circles optimised for the smaller sensors and focal lengths equivalent to those generally offered for existing 35 mm mount DSLRs, mostly in the wide angle range. These lenses tend not to be completely compatible with full frame sensors or 35 mm film because of the smaller imaging circle[3] and, with some Canon EF-S lenses, interfere with the reflex mirrors on full-frame bodies.

HD video capture

Since 2008, manufacturers have offered DSLRs which offer a movie mode capable of recording high definition motion video. A DSLR with this feature is often known as an HDSLR or DSLR video shooter.[4] The first DSLR introduced with an HD movie mode, the Nikon D90, captures video at 720p24 (1280x720 resolution at 24 frame/s). Other early HDSLRs capture video using a nonstandard video resolution or frame rate. For example, the Pentax K-7 uses a nonstandard resolution of 1536×1024, which matches the imager’s 3:2 aspect ratio. The Canon EOS 500D (Rebel T1i) uses a nonstandard frame rate of 20 frame/s at , along with a more conventional 720p30 format. In general, HDSLRs use the full imager area to capture HD video, though not all pixels (causing video artifacts to some degree). Compared to the much smaller image sensors found in the typical camcorder, the HDSLR’s much larger sensor yields distinctly different image characteristics.[5] HDSLRs can achieve much shallower depth of field and superior low-light performance. However, the low ratio of active pixels (to total pixels) is more susceptible to aliasing artifacts (such as moire patterns) in scenes with particular textures, and CMOS rolling shutter tends to 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 111 be more severe. Furthermore, due to the DSLR’s optical construction, HDSLRs typically lack one or more video functions found on standard dedicated camcorders, such as autofocus while shooting, powered zoom, and an electronic viewfinder/preview. These and other handling limitations prevent the HDSLR from being operated as a simple point- and-shoot camcorder, instead demanding some level of planning and skill for location shooting. Video functionality has continued to improve since the introduction of the HDSLR, including higher video resolution (such as 1080p24) and video bitrate, improved automatic control (autofocus) and manual exposure control, and support for formats compatible with high-definition television broadcast, Blu-ray disc mastering[6] or Digital Cinema Initiatives (DCI). The Canon EOS 5D Mark II (with the release of firmware version 2.0.3/2.0.4.[7]) and Panasonic Lumix GH1 were the first HDSLRs to offer broadcast compliant 1080p24 video, and since then the list of models with comparable functionality has grown considerably. The rapid maturation of HDSLR cameras has sparked a revolution in digital filmmaking, and the “Shot On DSLR” badge is a quickly growing phrase among independent filmmakers. Canon’s North American TV advertisements featuring the Rebel T1i have been shot using the T1i itself. An increased number of films, documentaries, television shows, and other productions are utilizing the quickly improving features. One such project was Canon’s “Story Beyond the Still” contest that asked filmmakers to collectively shoot a short film in 8 chapters, with each chapter being shot in only a couple of weeks and a winner was determined for each chapter, afterward the winners collaborated to shoot the final chapter of the story. Due to the affordability and convenient size of HDSLRs compared to professional movie cameras, The Avengers used five Canon EOS 5D Mark II and two Canon 7D to shoot the scenes from various vantage angles throughout the set and reduced the number of reshoots of complex action scenes.[8]

Sony ECM-CG50 shotgun-type for DSLR video capture

Manufacturers have sold optional accessories to optimize a DSLR camera as a video camera, such as a shotgun-type microphone, and an External EVF with 1.2 million pixels.[9]

Live preview

Main article: Live preview Early DSLRs lacked the ability to show the optical viewfinder’s image on the LCD display – a feature known as live preview. Live preview is useful in situations where the camera’s eye-level viewfinder cannot be used, such as where the camera is enclosed in a plastic waterproof case. In 2000, Olympus introduced the Olympus E-10, the first DSLR with live preview – albeit with an atypical fixed lens 112 CHAPTER 9. DAY 9

Nikon D90 in Liveview mode also usable for 720p HD video

design. In late 2008, some DSLRs from Canon, Nikon, Olympus, Panasonic, Leica, Pentax, Samsung and Sony all provided continuous live preview as an option. Additionally, the Fujifilm FinePix S5 Pro[10] offers 30 seconds of live preview. On almost all DSLRs that offer live preview via the primary sensor, the phase detection autofocus system does not work in the live preview mode, and the DSLR to a slower contrast system commonly found in point & shoot cameras. While even phase detection autofocus requires contrast in the scene, strict contrast detection autofocus is limited in its ability to find focus quickly, though it is somewhat more accurate. In 2012, Canon introduced hybrid autofocus technology to the DSLR in the EOS 650D/Rebel T4i, and introduced a more sophisticated version, which it calls “Dual Pixel CMOS AF”, with the EOS 70D. The technology allows certain pixels to act as both contrast-detection and phase-detection pixels, thereby greatly improving autofocus speed in live view (although it remains slower than pure phase detection). While several mirrorless cameras, plus Sony’s fixed-mirror SLTs, have similar hybrid AF systems, Canon is the only manufacturer that offers such a technology in DSLRs. A new feature via a separate software package introduced from Breeze Systems in October 2007, features live view from a distance. The software package is named “DSLR Remote Pro v1.5” and enables support for the Canon EOS 40D and 1D Mark III.[11]

Larger sensor sizes and better image quality

Main article: Image sensor format Image sensors used in DSLRs come in a range of sizes. The very largest are the ones used in "medium format" cameras, typically via a "digital back" which can be used as an alternative to a film back. Because of the manufacturing costs of these large sensors the price of these cameras is typically over $6,500 as of May 2014. "Full-frame" is the same size as 35 mm film (135 film, image format 24×36 mm); these sensors are used in DSLRs such as the Canon EOS-1D X Mark II, 5DS/5DSR, 5D Mark IV and 6D, and the Nikon D5, D810, D750, D610 and Df. Most modern DSLRs use a smaller sensor that is APS-C sized, which is approximately 22×15 mm, slightly smaller than the size of an APS-C film frame, or about 40% of the area of a full-frame sensor. Other sensor sizes found in DSLRs include the Four Thirds System sensor at 26% of full frame, APS-H sensors (used, for example, in the Canon EOS-1D Mark III) at around 61% of full frame, and the original Foveon X3 sensor at 33% of full frame 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 113

35 mm “full frame” 36×24 mm 864 mm²

APS-H (Canon) APS-C (Nikon, Sony, APS-C (Canon) 28.7×19 mm Pentax, Fuji etc.) 22.2×14.8 mm 548 mm² ≈23.6×15.7 mm 329 mm² ≈370 mm²

Foveon (Sigma) Four Thirds System 1″ (Nikon,Sony) 20.7×13.8 mm (Olympus, Panasonic) 13.2×8.8 mm 286 mm² 17.3×13 mm 116 mm² 225 mm²

2/3″ (Fuji, Nokia) 1/1.7″ 1/2.5″ 8.6×6.6 mm 7.6×5.7 mm 5.76×4.29 mm 58.1 mm² 43 mm² 25 mm²

Drawing showing the relative sizes of sensors used in current digital cameras.

(although as of 2013, current Foveon sensors are APS-C sized). Leica offers an “S-System” DSLR with a 30×45 mm array containing 37 million pixels.[12] This sensor is 56% larger than a full-frame sensor. The resolution of DSLR sensors is typically measured in megapixels. More expensive cameras and cameras with larger sensors tend to have higher megapixel ratings. A larger megapixel rating does not mean higher quality. Low 114 CHAPTER 9. DAY 9 light sensitivity is a good example of this. When comparing two sensors of the same size, for example two APS-C sensors one 12.1 MP and one 18 MP, the one with the lower megapixel rating will usually perform better in low light. This is because the size of the individual pixels is larger, and more light is landing on each pixel compared to the sensor with more megapixels. This is not always the case, because newer cameras that have higher megapixels also have better noise reduction software, and higher ISO settings to make up for the loss of light per pixel due to higher pixel density. [14]

Depth-of-field control

The lenses typically used on DSLRs have a wider range of apertures available to them, ranging from as large as f/0.9 to about f/32. Lenses for smaller sensor cameras rarely have true available aperture sizes much larger than f/2.8 or much smaller than f/5.6. To help extend the exposure range, some smaller sensor cameras will also incorporate an ND filter pack into the aperture mechanism.[15] The apertures that smaller sensor cameras have available give much more depth of field than equivalent angles of view on a DSLR. For example, a 6 mm lens on a 2/3″ sensor digicam has a field of view similar to a 24 mm lens on a 35 mm camera. At an aperture of f/2.8 the smaller sensor camera (assuming a crop factor of 4) has a similar depth of field to that 35 mm camera set to f/11.

Wider angle of view

Further information: Crop factor The angle of view of a lens depends upon its focal length and the camera’s image sensor size; a sensor smaller than

An APS-C format SLR (left) and a full-frame DSLR (right) show the difference in the size of the image sensors.

35 mm film format (36×24 mm frame) gives a narrower angle of view for a lens of a given focal length than a camera equipped with a full-frame (35 mm) sensor. As of 2016, only a few current DSLRs have full-frame sensors, including the Canon EOS-1D X Mark II, EOS 5D Mark IV, EOS 5DS/5DS R, and EOS 6D; and Nikon's D5, D610, D750, D810, and Df. The scarcity of full-frame DSLRs is partly a result of the cost of such large sensors. Medium format size sensors, such as those used in the Mamiya ZD among others, are even larger than full-frame (35 mm) sensors, and capable of even greater resolution, and are correspondingly more expensive. The impact of sensor size on field of view is referred to as the "crop factor" or “focal length multiplier”, which is a factor by which a lens focal length can be multiplied to give the full-frame-equivalent focal length for a lens. Typical APS-C sensors have crop factors of 1.5 to 1.7, so a lens with a focal length of 50 mm will give a field of view equal to that of a 75 mm to 85 mm lens on a 35 mm camera. The smaller sensors of Four Thirds System cameras have a crop factor of 2.0. 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 115

While the crop factor of APS-C cameras effectively narrows the angle of view of long-focus (telephoto) lenses, making it easier to take close-up images of distant objects, wide-angle lenses suffer a reduction in their angle of view by the same factor. DSLRs with “crop” sensor size have slightly more depth-of-field than cameras with 35 mm sized sensors for a given angle of view. The amount of added depth of field for a given focal length can be roughly calculated by multiplying the depth of field by the crop factor. Shallower depth of field is often preferred by professionals for portrait work and to isolate a subject from its background.

Unusual features

On July 13, 2007, FujiFilm announced the FinePix IS Pro, which uses Nikon F-mount lenses. This camera, in addition to having live preview, has the ability to record in the infrared and ultraviolet spectra of light.[16] In August 2010 Sony released series of DSLRs allowing 3D photography. It was accomplished by sweeping the camera horizontally or vertically in Sweep Panorama 3D mode. The picture could be saved as ultra-wide panoramic image or as 16:9 3D photography to be viewed on BRAVIA set.[17][18]

9.1.3 History

See also: History of the camera § Digital cameras In 1969 Willard S. Boyle and George E. Smith invented the first successful imaging technology using a digital sensor, a CCD (Charge-Coupled Device). CCD would allow the rapid development of digital photography. For their contribution to digital photography Boyle and Smith were awarded the Nobel Prize for Physics in 2009.[19] In 1975 Kodak engineer Steven Sasson invented the first digital still camera, which used a Fairchild 100×100 pixel CCD.[20] On August 25, 1981 Sony unveiled a prototype of the . This camera was an analog electronic camera that featured interchangeable lenses and a SLR viewfinder. In 1986, the Kodak Microelectronics Technology Division developed a 1.3 MP CCD image sensor, the first with more than 1 million pixels. In 1987, this sensor was integrated with a Canon F-1 film SLR body at the Kodak Federal Systems Division to create the first DSLR camera.[21] The digital back monitored the camera body battery current to sync the image sensor exposure to the film body shutter.[22][23] Digital images were stored on a tethered hard drive and processed for histogram feedback to the user. This first camera was created for the U.S. Government, and was followed by several other models intended for government use, and eventually the first commercial DSLR, launched by Kodak in 1991.[24][25][26] In 1995, Nikon co-developed the Nikon E series with Fujifilm. The E series included the Nikon E2/E2S, Nikon E2N/E2NS and the Nikon E3/E3S, with the E3S released in December 1999. In 1999, Nikon announced the . The D1’s body was similar to Nikon’s professional 35 mm film SLRs, and it had the same lens mount, allowing the D1 to use Nikon’s existing line of AI/AIS manual-focus and AF lenses. Although Nikon and other manufacturers had produced digital SLR cameras for several years prior, the D1 was the first professional digital SLR that displaced Kodak’s then-undisputed reign over the professional market.[27] Over the next decade, other camera manufacturers entered the DSLR market, including Canon, Kodak, Fujifilm, Minolta (later Konica Minolta, and ultimately acquired by Sony), Pentax (whose camera division is now owned by Ricoh), Olympus, Panasonic, Samsung, Sigma, and Sony. In January 2000, Fujifilm announced the FinePix S1 Pro, the first consumer-level DSLR. In November 2001, Canon released its 4.1 megapixel EOS-1D, the brand’s first professional digital body. In 2003, Canon introduced the 6.3 megapixel EOS 300D SLR camera (known in the United States and Canada as the Digital Rebel and in Japan as the Kiss Digital) with an MSRP of US$999, aimed at the consumer market. Its commercial success encouraged other manufacturers to produce competing digital SLRs, lowering entry costs and allowing more amateur photographers to purchase DSLRs. In 2004, Konica Minolta released the Konica Minolta Maxxum 7D, the first DSLR with in-body image stabilization[28] which later on become standard in Pentax, Olympus and Sony Alpha cameras. In early 2008, Nikon released the D90, the first DSLR to feature video recording. Since then all major companies offer cameras with this functionality. 116 CHAPTER 9. DAY 9

Kodak DCS 100, based on a body with Digital Storage Unit, released in May 1991

Since then the number of megapixels in imaging sensors have increased steadily, with most companies focusing on high ISO performance, speed of focus, higher frame rates, the elimination of digital 'noise' produced by the imaging sensor, and price reductions to lure new customers. In June 2012, Canon announced the first DSLR to feature a touchscreen, the EOS 650D/Rebel T4i/Kiss X6i. Al- though this feature had been widely used on both compact cameras and mirrorless models, it had not made an ap- pearance in a DSLR until the 650D.[29] 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 117

Nikon NASA F4 back view with Electronics Box, launched on STS-48 September 1991

Market share

The DSLR market is dominated by Japanese companies and the top five manufacturers are Japanese: Canon, Nikon, Olympus, Pentax, and Sony. Other manufacturers of DSLRs include Mamiya, Sigma, Leica (German), and Hasselblad (Swedish). In 2007, Canon edged out Nikon with 41% of worldwide sales to the latter’s 40%, followed by Sony and Olympus each with approximately 6% market share.[30] In the Japanese domestic market, Nikon captured 43.3% to Canon’s 39.9%, with Pentax a distant third at 6.3%.[31] In 2008, Canon's and Nikon's offerings took the majority of sales.[32] In 2010, Canon controlled 44.5% of the DSLR 118 CHAPTER 9. DAY 9

market, followed by Nikon with 29.8% and Sony with 11.9%.[33] For Canon and Nikon, digital SLRs are their biggest source of profits. For Canon, their DSLRs brought in four times the profits from compact digital cameras, while Nikon earned more from DSLRs and lenses than with any other product.[34][35] Olympus and Panasonic have since exited the DSLR market and now focus on producing mirrorless cameras. In 2013, after a decade of double-digit growth, DSLR (along with MILC) sales are down 15 percent. This may be due to some low-end DSLR users choosing to use a smartphone instead. The market intelligence firm IDC predicts Nikon will be out of business in five years if the trend continues. The market has shifted from being driven by hardware to software, and camera manufacturers have not been keeping up.[36] To illustrate the trend, in September 2013 Olympus announced they would stop development of DSLR cameras and will focus on the development of MILC.[37]

Present-day models

Pentax K-3

Currently DSLRs are widely used by consumers and professional still photographers. Well established DSLRs cur- rently offer a larger variety of dedicated lenses and other photography equipment. Mainstream DSLRs (in full- frame or smaller image sensor format) are produced by Canon, Nikon, Pentax, and Sigma. Pentax, Phase One, Hasselblad, and Mamiya Leaf produce expensive, high-end medium-format DSLRs, including some with removable sensor backs. Contax, Fujifilm, Kodak, Panasonic, Olympus, Samsung previously produced DSLRs, but now either offer non-DSLR systems or have left the camera market entirely. Konica Minolta's line of DSLRs was purchased by Sony.

• Canon’s current 2016 EOS digital line includes the Canon EOS 1300D/Rebel T6, 100D/SL1, 750D/T6i, 760D/T6s, 80D, 7D Mark II, 6D, 5D Mark IV, 5Ds and 5Ds R and the 1D X Mark II. All Canon DSLRs with three- and four-digit model numbers, as well as the 7D Mark II, have APS-C sensors. The 6D, 5D series, and 1D X are full-frame. As of 2016, all current Canon DSLRs use CMOS sensors. 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 119

Canon EOS 70D APS-C digital SLR with lens removed

• Nikon has a broad line of DSLRs, most in direct competition with Canon’s offerings, including the D3400, D5500, D7200 and D500 with APS-C sensors, and the D610, D750, D810, D5, D3X and the Df with full- frame sensors.

• Leica produces the S2, a medium format DSLR.

• Pentax currently offers the K-3 II, K-S2 and K-S1, all of which use an APS-C sensor.[38] These models offer extensive backwards compatibility, accepting all Pentax K mount lenses, which started being made in 1975. Pentax also offers the , which is a medium format camera, and, like Pentax' medium format film cameras, compatible with Pentax' 645 system lenses. In 2016, Pentax introduced its first full-frame DSLR, the Pentax K-1.

• Sigma produces DSLRs using the Foveon X3 sensor, rather than the conventional Bayer sensor. This is claimed to give higher colour resolution, although headline pixel counts are lower than conventional Bayer-sensor cam- eras. It currently offers the entry-level SD15 and the professional SD1. Sigma is the only DSLR manufacturer which sells lenses for other brands’ lens mounts.

• Sony has modified the DSLR formula in favor of single-lens translucent (SLT) cameras,[39] which are still technically DSLRs, but feature a fixed mirror that allows most light through to the sensor while reflecting some light to the autofocus sensor. Sony’s SLTs feature full-time phase detection autofocus during video recording as well as continuous shooting of up to 12 frame/s. The α series, whether traditional SLRs or SLTs, offers in- body sensor-shift image stabilization and retains the Minolta AF lens mount. As of February 2015, the lineup included the Alpha 58, the semipro Alpha 77 II, and the professional full-frame Alpha 99 II. The translucent (transmissive) fixed mirror allows 70 percent of the light to pass through onto the imaging sensor, meaning a 1/3rd stop loss light, but the rest of this light is continuously reflected onto the camera’s phase detection AF sensor for fast autofocus for both the viewfinder and live view on the rear screen, even during video and continuous shooting. The reduced number of moving parts also makes for faster shooting speeds for its class. This arrangement means that the SLT cameras use an electronic viewfinder as opposed to an optical viewfinder, which some consider a disadvantage, but does have the advantage of a live preview of the shot with current settings, anything displayed on the rear screen is displayed on the viewfinder, and handles bright situations well.[40] 120 CHAPTER 9. DAY 9

Nikon D4S full-frame (FX) digital SLR camera

9.1.4 DSLRs compared to other digital cameras

The reflex design scheme is the primary difference between a DSLR and other digital cameras. In the reflex design scheme, the image captured on the camera’s sensor is also the image that is seen through the view finder. Light travels through a single lens and a mirror is used to reflect a portion of that light through the view finder – hence the name Single Lens Reflex. While there are variations among point-and-shoot cameras, the typical design exposes the sensor constantly to the light projected by the lens, allowing the camera’s screen to be used as an electronic viewfinder. However, LCDs can be difficult to see in very bright sunlight. Compared to some low cost cameras that provide an optical viewfinder that uses a small auxiliary lens, the DSLR design has the advantage of being parallax-free: it never provides an off-axis view. A disadvantage of the DSLR optical viewfinder system is that when it is used, it prevents using the LCD for viewing and composing the picture. Some people prefer to compose pictures on the display – for them this has become the de facto way to use a camera. Depending on the viewing position of the reflex mirror (down or up), the light from the scene can only reach either the viewfinder or the sensor. Therefore, many early DSLRs did not provide "live preview" (i.e., focusing, framing, and depth-of-field preview using the display), a facility that is always available on digicams. Today most DSLRs can alternate between live view and viewing through an optical viewfinder. 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 121

Optical view image and digitally created image

The larger, advanced digital cameras offer a non-optical electronic through-the-lens (TTL) view, via an eye-level electronic viewfinder (EVF) in addition to the rear LCD. The difference in view compared to a DSLR is that the EVF shows a digitally created image, whereas the viewfinder in a DSLR shows an actual optical image via the reflex viewing system. An EVF image has lag time (that is, it reacts with a delay to view changes) and has a lower resolution than an optical viewfinder but achieves parallax-free viewing using less bulk and mechanical complexity than a DSLR with its reflex viewing system. Optical viewfinders tend to be more comfortable and efficient, especially for action photography and in low-light conditions. Compared to digital cameras with LCD electronic viewfinders, there is no time lag in the image: it is always correct as it is being “updated” at the speed of light. This is important for action or , or any other situation where the subject or the camera is moving quickly. Furthermore, the “resolution” of the viewed image is much better than that provided by an LCD or an electronic viewfinder, which can be important if manual focusing is desired for precise focusing, as would be the case in macro photography and “micro-photography” (with a microscope). An optical viewfinder may also cause less eye-strain. However, electronic viewfinders may provide a brighter display in low light situations, as the picture can be electronically amplified.

Performance differences

DSLR cameras often have image sensors of much larger size and often higher quality, offering lower noise,[41] which is useful in low light. Although mirrorless digital cameras with APS-C and full frame sensors exist, most full frame and medium format sized image sensors are still seen in DSLR designs. DSLRs generally offer faster and more responsive performance, with less shutter lag, faster autofocus systems, and higher frame rates.[42] Although some micro 4/3 cameras have frame rates that rival those of professional level DSLRs. The downside of these cameras being that they do not have an optical viewfinder, making it difficult to focus on moving subjects or in situations where a fast burst mode would be beneficial. Other digital cameras were once significantly slower in image capture (time measured from pressing the shutter release to the writing of the digital image to the storage medium) than DSLR cameras, but this situation is changing with the introduction of faster capture memory cards and faster in-camera processing chips. Still, compact digital cameras are not suited for action, wildlife, sports and other photography requiring a high burst rate (frames per second). Simple point-and-shoot cameras rely almost exclusively on their built-in automation and machine intelligence for capturing images under a variety of situations and offer no manual control over their functions, a trait which makes them unsuitable for use by professionals, enthusiasts and proficient consumers (aka “prosumers”). Bridge cameras provide some degree of manual control over the camera’s shooting modes, and some even have hotshoes and the option to attach lens accessories such as filters and secondary converters. DSLRs typically provide the photographer with full control over all the important parameters of photography and have the option to attach additional accessories[43] including hot shoe-mounted flash units, battery grips for additional power and hand positions, external light meters, and remote controls. DSLRs typically also have fully automatic shooting modes. DSLRs have a larger focal length for the same field of view, which allows creative use of depth of field effects.However, small digital cameras can focus better on closer objects than typical DSLR lenses.

Sensor size The sensors used in current DSLRs ("Full-frame" which is the same size as 35 mm film (135 film, image format 24×36 mm), APS-C sized, which is approximately 22×15 mm, and Four Thirds System) are typically much larger than the sensors found in other types of digital cameras. Entry-level compact cameras typically use sensors known as 1/2.5″, which is 3% the size of a full frame sensor. There are bridge cameras (also known as premium compact cameras or enthusiast point-and-shoot cameras) that offer sensors larger than 1/2.5″ but most still fall short of the larger sizes widely found on DSLR. Examples include the Sigma DP1, which uses a Foveon X3 sensor; the ; the Canon PowerShot G1 X, which uses a 1.5″ (18.7×14 mm) sensor that is slightly larger than the Four Thirds standard and is 30% of a full-frame sensor; the Nikon Coolpix A, which uses an APS-C sensor of the same size as those found in the company’s DX-format DSLRs; and two models from Sony, the RX100 with a 1″-type (13.2×8.8 mm) sensor with about half the area of Four Thirds and the full-frame Sony RX1. These premium compacts are often comparable to entry-level DSLRs in price, with the smaller size and weight being a tradeoff for the smaller sensor. [14] 122 CHAPTER 9. DAY 9

Fixed or interchangeable lenses

Unlike DSLRs, most digital cameras lack the option to change the lens. Instead, most compact digital cameras are manufactured with a zoom lens that covers the most commonly used fields of view. Having fixed lenses, they are limited to the focal lengths they are manufactured with, except for what is available from attachments. Manufacturers have attempted (with increasing success) to overcome this disadvantage by offering extreme ranges of focal length on models known as superzooms, some of which offer far longer focal lengths than readily available DSLR lenses. There are now available perspective-correcting (PC) lenses for DSLR cameras, providing some of the attributes of view cameras. Nikon introduced the first PC lens, fully manual, in 1961. Recently, however, some manufacturers have introduced advanced lenses that both shift and tilt and are operated with automatic aperture control. However, since the introduction of the Micro Four Thirds system by Olympus and Panasonic in late 2008, mirrorless interchangeable lens cameras are now widely available so the option to change lenses is no longer unique to DSLRs. Cameras for the micro four thirds system are designed with the option of a replaceable lens and accept lenses that conform to this proprietary specification. Cameras for this system have the same sensor size as the Four Thirds System but do not have the mirror and pentaprism, so as to reduce the distance between the lens and sensor. Panasonic released the first Micro Four Thirds camera, the Lumix DMC-G1. Several manufacturers have announced lenses for the new Micro Four Thirds mount, while older Four Thirds lenses can be mounted with an adapter (a mechanical spacer with front and rear electrical connectors and its own internal firmware). A similar mirror-less interchangeable lens camera, but with an APS-C-sized sensor, was announced in January 2010: the Samsung NX10. On 21 September 2011, Nikon announced with the Nikon 1 a series of high-speed MILCs. A handful of rangefinder cameras also support interchangeable lenses. Six digital rangefinders exist: the Epson R-D1 (APS-C-sized sensor), the Leica M8 (APS-H-sized sensor), both smaller than 35 mm film rangefinder cameras, and the Leica M9, M9-P, M Monochrom and M (all full-frame cameras, with the Monochrom shooting exclusively in black-and-white). In common with other interchangeable lens designs, DSLRs must contend with potential contamination of the sensor by dust particles when the lens is changed (though recent dust reduction systems alleviate this). Digital cameras with fixed lenses are not usually subject to dust from outside the camera settling on the sensor. DSLRs generally have greater cost, size, and weight.[44] They also have louder operation, due to the SLR mirror mechanism.[45] Sony’s fixed mirror design manages to avoid this problem. However, that design has the disadvantage that some of the light received from the lens is diverted by the mirror and thus the image sensor receives about 30% less light compared to other DSLR designs.

9.1.5 See also

• Mirrorless interchangeable-lens camera • Box camera • Comparison of digital single-lens reflex cameras • Full-frame digital SLR • Rangefinder camera • Single-lens reflex camera • Single-lens translucent camera • Twin-lens reflex camera

9.1.6 References

[1] “Choosing a DSLR Camera”. Retrieved 22 August 2015.

[2] Canon Europa N.V. and Canon Europe Ltd 2002-2015. “Canon Professional Network - The EOS Integrated Cleaning System”. Canon Professional Network. Retrieved 22 August 2015.

[3] “How Nikon bettered Canon with full-frame SLRs”. 2007-12-18. Retrieved 2009-08-13.

[4] “10 Must Read HDSLR Guides For Filmmakers”. DSLR Video Shooter. Retrieved 22 August 2015. 9.1. DIGITAL SINGLE-LENS REFLEX CAMERA 123

[5] “Canon DLC: Article: What’s New in the EOS Rebel T1i: HD Movie Mode”. Retrieved 22 August 2015.

[6] “Blue-ray Disc Format White Paper” (PDF). March 2005. Retrieved 2009-10-03.

[7] “5D Mark II Firmware Announcement”. Canonrumors.com. 2010-03-01. Retrieved 2010-12-30.

[8] “Canon EOS 5D Mark II and EOS 7D Digital SLR Cameras of Choice for Stunts and Action Work on Set of “Marvel’s The Avengers"". Retrieved May 21, 2012.

[9] “Zacuto Announces EVF Viewfinder With 70% Less Resolution Than the Redrock Micro?". NoFilmSchool. Retrieved 2011-01-02.

[10] Simon Joinson (July 2007). “Fujifilm FinePix S5 Pro Review”. Digital Photography Review. Retrieved 2007-12-07.

[11] dpreview.com (October 2, 2007). “Live view from a distance with DSLR Remote Pro v1.5”. Digital Photography Review. Retrieved 2007-10-07.

[12] Tuesday, 23 September 2008 00:03 GMT (2008-09-23). “Leica S2 with 56% larger sensor than full frame”. Dpre- view.com. Retrieved 2010-12-30.

[13] Defined here as the ratio of the diagonal of a full 35 frame to that of the sensor format, that is CF=diag₃₅ / diagₑₒᵣ.

[14] Bockaert, Vincent. “Sensor sizes”. Digital Photography Review. Retrieved 2007-12-06.

[15] Thursday, 14 September 2006 10:04 GMT (2006-09-14). “Canon PowerShot G7: Digital Photography Review”. Dpre- view.com. Retrieved 2010-12-30.

[16] “Fujifilm FinePix IS Pro digital camera specifications: Digital Photography Review”. Dpreview.com. Archived from the original on 2010-12-28. Retrieved 2010-12-30.

[17] “Sony introduces high performance DSLR cameras with Full HD video Fully featured α580 with newly developed 16.2M Exmor APS HD CMOS censor, up to 7fps shooting, and Auto HDR” (Press release). Sony. 2010-08-24. Archived from the original on 2010-08-30. Retrieved 2010-09-12.

[18] “A580 DSLR interchangeable lens camera”. Retrieved 2010-09-12.

[19] “The 2009 Nobel Prize in Physics – Press Release”. Nobelprize.org. 2009-10-06. Retrieved 2013-10-10.

[20] Jarvis, Audley (2008-05-09). “How Kodak invented the digital camera in 1975”. Techradar.com. Retrieved 2011-06-26.

[21] Museum, George Eastman (2012-12-19). “Historic New Acquisition at Eastman House”. . Re- trieved 2016-12-30.

[22] , McGarvey, James E., “Method and circuit for converting a conventional camera into an electro-optical camera”

[23] “Electro-Optic Camera: The first DSLR”. eocamera.jemcgarvey.com. Retrieved 2016-12-30.

[24] Todd A. Jackson; Cynthia S. Bell (Feb 1991). “A 1.3-megapixel-resolution portable CCD electronic still camera”. Proc. SPIE 1448, Camera and Input Scanner Systems 2. Retrieved 2013-10-29.

[25] Bell, Cynthia S. (Feb 1991). “Lens Evaluation for Electronic Photography”. Proc. SPIE 1448, Camera and Input Scanner Systems 59. Retrieved 2013-10-29.

[26] Bell, Cynthia S.; Jackson, Todd A. “Electronic Still Camera and Film Camera Comparison Experiment”.

[27] Askey, Phil (2000-11-27). “Nikon D1 Review: 1. Intro”. Digital Photography Review. Retrieved 2009-10-25.

[28] Konica Minolta (2004-09-15). “KONICA MINOLTA INTRODUCES THE MAXXUM 7D – WORLD'S FIRST*1 DIGITAL SLR CAMERA WITH REVOLUTIONARY BODY-INTEGRAL, ANTI-SHAKE TECHNOLOGY”. DPRe- view.com. Retrieved 2007-02-03.

[29] Westlake, Andy (June 2012). “Canon EOS 650D (Rebel T4i) Hands-on Preview”. Digital Photography Review. Retrieved 2012-06-10.

[30] “IDC on 2007 Sales: Nikon, Sony Gain in dSLRs; Samsung Up, Kodak Holds On in Digicams”. [imaging-resource.com]. 2008-04-07. Retrieved 2008-04-08.

[31] "'Big two' continue to dominate Japan”. DPreview.com. 2008-01-11. Retrieved 2008-04-08.

[32] “Canon vs Nikon Digital SLR Cameras”. Digital-slr-guide.com. Retrieved 2013-10-10.

[33] "'Sony, Nikon Narrow Gap to Canon With New Digital Camera Models’". Bloomberg.com. 2011-04-15. 124 CHAPTER 9. DAY 9

[34] “Canon camera profits rise despite falling sales: Digital Photography Review”. Dpreview.com. Retrieved 2013-10-10.

[35] Yasu, Mariko (2011-09-08). “Canon Clinging to Mirrors Means Opportunity for Sony Cameras”. Businessweek. Archived from the original on 2013-05-28. Retrieved 2013-10-10.

[36] “Consumer DSLRs “dead in 5 years"". Retrieved December 30, 2013.

[37] “Mirrorless cameras offer glimmer of hope to makers”. Retrieved December 31, 2013.

[38] “PentaxWebstore.com: Digital SLR”. Retrieved 2013-11-05.

[39] “Learn how our SLT cameras work”. Sony. 2009-07-30. Retrieved 2013-10-10.

[40] “Sony Alpha a99 review”. November 22, 2012.

[41] “Sensor Sizes”.

[42] “The Beginner’s Guide To DSLR Cameras”. 2016-05-20.

[43] “10 Reasons to Buy a DSLR Camera”. 2006-11-05. Archived from the original on 2008-05-23.

[44] “10 Reasons NOT to Buy a DSLR Camera”. 2006-11-14.

[45] “REVIEW: Canon Powershot S3 IS”. July 2006.

9.1.7 External links

• Media related to Digital SLR cameras at Wikimedia Commons

9.2 CMOS

For other uses, see CMOS (disambiguation). Complementary metal–oxide–semiconductor, abbreviated as CMOS /ˈsiːmɒs/, is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for several analog circuits such as image sensors (CMOS sensor), data converters, and highly integrated transceivers for many types of communication. In 1963, while working for , Frank Wanlass patented CMOS (US patent 3,356,858). CMOS is also sometimes referred to as complementary-symmetry metal–oxide–semiconductor (or COS-MOS).[1] The words “complementary-symmetry” refer to the fact that the typical design style with CMOS uses complementary and symmetrical pairs of p-type and n-type metal oxide semiconductor field effect transistors () for logic functions.[2] Two important characteristics of CMOS devices are high noise immunity and low static power consumption.[3] Since one transistor of the pair is always off, the series combination draws significant power only momentarily during switching between on and off states. Consequently, CMOS devices do not produce as much waste heat as other forms of logic, for example transistor–transistor logic (TTL) or NMOS logic, which normally have some standing current even when not changing state. CMOS also allows a high density of logic functions on a chip. It was primarily for this reason that CMOS became the most used technology to be implemented in VLSI chips. The phrase “metal–oxide–semiconductor” is a reference to the physical structure of certain field-effect transistors, having a metal gate electrode placed on top of an oxide , which in turn is on top of a semiconductor material. Aluminium was once used but now the material is polysilicon. Other metal gates have made a comeback with the advent of high-k materials in the CMOS process, as announced by IBM and Intel for the 45 nanometer node and beyond.[4]

9.2.1 Technical details

“CMOS” refers to both a particular style of digital circuitry design and the family of processes used to implement that circuitry on integrated circuits (chips). CMOS circuitry dissipates less power than logic families with resistive loads. Since this advantage has increased and grown more important, CMOS processes and variants have come to 9.2. CMOS 125

CMOS inverter (NOT logic gate)

dominate, thus the vast majority of modern integrated circuit manufacturing is on CMOS processes.[5] As of 2010, CPUs with the best performance per watt each year have been CMOS static logic since 1976. CMOS circuits use a combination of p-type and n-type metal–oxide–semiconductor field-effect transistor (MOS- FETs) to implement logic gates and other digital circuits. Although CMOS logic can be implemented with discrete devices for demonstrations, commercial CMOS products are integrated circuits composed of up to billions of tran- sistors of both types, on a rectangular piece of silicon of between 10 and 400 mm2. CMOS always uses all enhancement-mode MOSFETs (in other words, a zero gate-to-source voltage turns the tran- sistor off).

9.2.2 Inversion

CMOS circuits are constructed in such a way that all PMOS transistors must have either an input from the voltage source or from another PMOS transistor. Similarly, all NMOS transistors must have either an input from ground or from another NMOS transistor. The composition of a PMOS transistor creates low resistance between its source and drain contacts when a low gate voltage is applied and high resistance when a high gate voltage is applied. On the other hand, the composition of an NMOS transistor creates high resistance between source and drain when a low gate voltage is applied and low resistance when a high gate voltage is applied. CMOS accomplishes current reduction 126 CHAPTER 9. DAY 9

Static CMOS inverter

by complementing every nMOSFET with a pMOSFET and connecting both gates and both drains together. A high voltage on the gates will cause the nMOSFET to conduct and the pMOSFET to not conduct, while a low voltage on the gates causes the reverse. This arrangement greatly reduces power consumption and heat generation. However, during the switching time, both MOSFETs conduct briefly as the gate voltage goes from one state to another. This induces a brief spike in power consumption and becomes a serious issue at high frequencies. The image on the right shows what happens when an input is connected to both a PMOS transistor (top of diagram) and an NMOS transistor (bottom of diagram). When the voltage of input A is low, the NMOS transistor’s channel is in a high resistance state. This limits the current that can flow from Q to ground. The PMOS transistor’s channel is in a low resistance state and much more current can flow from the supply to the output. Because the resistance between the supply voltage and Q is low, the voltage drop between the supply voltage and Q due to a current drawn from Q is small. The output therefore registers a high voltage. On the other hand, when the voltage of input A is high, the PMOS transistor is in an OFF (high resistance) state so it would limit the current flowing from the positive supply to the output, while the NMOS transistor is in an ON (low resistance) state, allowing the output from drain to ground. Because the resistance between Q and ground is low, the voltage drop due to a current drawn into Q placing Q above ground is small. This low drop results in the output registering a low voltage. In short, the outputs of the PMOS and NMOS transistors are complementary such that when the input is low, the 9.2. CMOS 127

output is high, and when the input is high, the output is low. Because of this behavior of input and output, the CMOS circuit’s output is the inverse of the input. The power supplies for CMOS are called VDD and VSS, or VCC and Ground(GND) depending on the manufacturer. VDD and VSS are carryovers from conventional MOS circuits and stand for the drain and source supplies.[6] These do not apply directly to CMOS, since both supplies are really source supplies. VCC and Ground are carryovers from TTL logic and that nomenclature has been retained with the introduction of the 54C/74C line of CMOS.

Duality

An important characteristic of a CMOS circuit is the duality that exists between its PMOS transistors and NMOS transistors. A CMOS circuit is created to allow a path always to exist from the output to either the power source or ground. To accomplish this, the set of all paths to the voltage source must be the complement of the set of all paths to ground. This can be easily accomplished by defining one in terms of the NOT of the other. Due to the De Morgan’s laws based logic, the PMOS transistors in parallel have corresponding NMOS transistors in series while the PMOS transistors in series have corresponding NMOS transistors in parallel.

Logic

More complex logic functions such as those involving AND and OR gates require manipulating the paths between gates to represent the logic. When a path consists of two transistors in series, both transistors must have low resistance to the corresponding supply voltage, modelling an AND. When a path consists of two transistors in parallel, either one or both of the transistors must have low resistance to connect the supply voltage to the output, modelling an OR. Shown on the right is a circuit diagram of a NAND gate in CMOS logic. If both of the A and B inputs are high, then both the NMOS transistors (bottom half of the diagram) will conduct, neither of the PMOS transistors (top half) will conduct, and a conductive path will be established between the output and V (ground), bringing the output low. If both of the A and B inputs are low, then neither of the NMOS transistors will conduct, while both of the PMOS transistors will conduct, establishing a conductive path between the output and V (voltage source), bringing the output high. If either of the A or B inputs is low, one of the NMOS transistors will not conduct, one of the PMOS transistors will, and a conductive path will be established between the output and V (voltage source), bringing the output high. As the only configuration of the two inputs that results in a low output is when both are high, this circuit implements a NAND (NOT AND) logic gate. An advantage of CMOS over NMOS logic is that both low-to-high and high-to-low output transitions are fast since the (PMOS) pull-up transistors have low resistance when switched on, unlike the load in NMOS logic. In addition, the output signal swings the full voltage between the low and high rails. This strong, more nearly symmetric response also makes CMOS more resistant to noise. See Logical effort for a method of calculating delay in a CMOS circuit.

Example: NAND gate in physical layout

This example shows a NAND logic device drawn as a physical representation as it would be manufactured. The physical layout perspective is a “bird’s eye view” of a stack of layers. The circuit is constructed on a P-type substrate. The polysilicon, diffusion, and n-well are referred to as “base layers” and are actually inserted into trenches of the P-type substrate. (See steps 1 to 6 in the process diagram below right) The contacts penetrate an insulating layer between the base layers and the first layer of metal (metal1) making a connection. The inputs to the NAND (illustrated in green color) are in polysilicon. The CMOS transistors (devices) are formed by the intersection of the polysilicon and diffusion; N diffusion for the N device & P diffusion for the P device (illustrated in salmon and yellow coloring respectively). The output (“out”) is connected together in metal (illustrated in coloring). Connections between metal and polysilicon or diffusion are made through contacts (illustrated as black squares). The physical layout example matches the NAND logic circuit given in the previous example. The N device is manufactured on a P-type substrate while the P device is manufactured in an N-type well (n-well). A P-type substrate “tap” is connected to VSS and an N-type n-well tap is connected to VDD to prevent latchup. 128 CHAPTER 9. DAY 9

9.2.3 Power: switching and leakage

CMOS logic dissipates less power than NMOS logic circuits because CMOS dissipates power only when switching (“dynamic power”). On a typical ASIC in a modern 90 nanometer process, switching the output might take 120 picoseconds, and happens once every ten nanoseconds. NMOS logic dissipates power whenever the transistor is on, because there is a current path from V to V through the load and the n-type network. Static CMOS gates are very power efficient because they dissipate nearly zero power when idle. Earlier, the power consumption of CMOS devices was not the major concern while designing chips. Factors like speed and area domi- nated the design parameters. As the CMOS technology moved below sub-micron levels the power consumption per unit area of the chip has risen tremendously. Broadly classifying, power dissipation in CMOS circuits occurs because of two components:

Static dissipation

Subthreshold conduction when the transistors are off Both NMOS and PMOS transistors have a gate–source threshold voltage, below which the current (called sub threshold current) through the device drops exponentially. Historically, CMOS designs operated at supply voltages much larger than their threshold voltages (V might have been 5 V, and V for both NMOS and PMOS might have been 700 mV). A special type of the CMOS transistor with near zero threshold voltage is the native transistor.

Tunnelling current through gate oxide SiO2 is a good insulator, but at very small thickness levels electrons can tunnel across the very thin insulation; the probability drops off exponentially with oxide thickness. Tunnelling current becomes very important for transistors below 130 nm technology with gate oxides of 20 Å or thinner.

Leakage current through reverse-biased diodes Small reverse leakage currents are formed due to formation of reverse bias between diffusion regions and wells (for e.g., p-type diffusion vs. n-well), wells and substrate (for e.g., n-well vs. p-substrate). In modern process diode leakage is very small compared to sub threshold and tunnelling currents, so these may be neglected during power calculations.

Contention current in ratioed circuit

Dynamic dissipation

Charging and discharging of load CMOS circuits dissipate power by charging the various load capacitances (mostly gate and wire capacitance, but also drain and some source capacitances) whenever they are switched. In one complete cycle of CMOS logic, current flows from VDD to the load capacitance to charge it and then flows from the charged load capacitance (CL) to ground during discharge. Therefore, in one complete charge/discharge cycle, a total of Q=CLVDD is thus transferred from VDD to ground. Multiply by the switching frequency on the load capacitances to get the current used, and multiply by the average voltage again to get the characteristic switching power dissipated by a CMOS device: P = 0.5CV 2f . Since most gates do not operate/switch at every clock cycle, they are often accompanied by a factor α , called the activity factor. Now, the dynamic power dissipation may be re-written as P = αCV 2f . A clock in a system has an activity factor α=1, since it rises and falls every cycle. Most data has an activity factor of 0.1.[7] If correct load capacitance is estimated on a node together with its activity factor, the dynamic power dissipation at that node can be calculated effectively.

Short-circuit power dissipation Since there is a finite rise/fall time for both pMOS and nMOS, during transition, for example, from off to on, both the transistors will be on for a small period of time in which current will find a path directly from VDD to ground, hence creating a short-circuit current. Short-circuit power dissipation increases with rise and fall time of the transistors. An additional form of power consumption became significant in the 1990s as wires on chip became narrower and the long wires became more resistive. CMOS gates at the end of those resistive wires see slow input transitions. During 9.2. CMOS 129 the middle of these transitions, both the NMOS and PMOS logic networks are partially conductive, and current flows directly from VDD to VSS. The power thus used is called crowbar power. Careful design which avoids weakly driven long skinny wires ameliorates this effect, but crowbar power can be a substantial part of dynamic CMOS power. To speed up designs, manufacturers have switched to constructions that have lower voltage thresholds but because of this a modern NMOS transistor with a V of 200 mV has a significant subthreshold leakage current. Designs (e.g. desktop processors) which include vast numbers of circuits which are not actively switching still consume power because of this leakage current. Leakage power is a significant portion of the total power consumed by such designs. Multi-threshold CMOS (MTCMOS), now available from foundries, is one approach to managing leakage power. With MTCMOS, high V transistors are used when switching speed is not critical, while low V transistors are used in speed sensitive paths. Further technology advances that use even thinner gate have an additional leakage component because of current tunnelling through the extremely thin gate dielectric. Using high-k dielectrics instead of silicon dioxide that is the conventional gate dielectric allows similar device performance, but with a thicker gate insulator, thus avoiding this current. Leakage power reduction using new material and system designs is critical to sustaining scaling of CMOS.[8]

9.2.4 Analog CMOS

Besides digital applications, CMOS technology is also used in analog applications. For example, there are CMOS operational amplifier ICs available in the market. Transmission gates may be used as analog multiplexers instead of signal relays. CMOS technology is also widely used for RF circuits all the way to frequencies, in mixed-signal (analog+digital) applications.

9.2.5 Temperature range

Conventional CMOS devices work over a range of −55 °C to +125 °C. There were theoretical indications as early as August 2008 that silicon CMOS will work down to −233 °C (40 K).[9] Functioning temperatures near 40 K have since been achieved using overclocked AMD Phenom II processors with a combination of liquid nitrogen and liquid helium cooling.[10]

9.2.6 Single-electron CMOS transistors

Ultra small (L = 20 nm, W = 20 nm) CMOS transistors achieve the single-electron limit when operated at cryogenic temperature over a range of −269 °C (4 K) to about −258 °C (15 K). The transistor displays Coulomb blockade due to progressive charging of electrons one by one. The number of electrons confined in the channel is driven by the gate voltage, starting from an occupation of zero electrons, and it can be set to 1 or many.[11]

9.2.7 See also

• Active pixel sensor

• Beyond CMOS

• Electric (software) – Used to lay out CMOS circuits

• FEOL (front-end-of-line) – The first part of IC fabrication process

• Gate equivalent – A technology-independent measure of circuit complexity

• HCMOS – High-speed CMOS 1982

• Magic (software) – Used to lay out CMOS circuits

• MOSFET 130 CHAPTER 9. DAY 9

9.2.8 References

[1] COS-MOS was an RCA trademark, which forced other manufacturers to find another name —CMOS

[2] “What is CMOS Memory?". Wicked Sago. Retrieved 3 March 2013.

[3] Fairchild. Application Note 77. “CMOS, the Ideal Logic Family”. 1983.

[4] Intel 45nm Hi-k Silicon Technology

[5] Baker, R. Jacob (2008). CMOS: circuit design, layout, and simulation (Second ed.). Wiley-IEEE. p. xxix. ISBN 978-0- 470-22941-5.

[6] http://www.fairchildsemi.com/an/AN/AN-77.pdf

[7] K. Moiseev, A. Kolodny and S. Wimer, “Timing-aware power-optimal ordering of signals”, ACM Transactions on Design Automation of Electronic Systems, Volume 13 Issue 4, September 2008, ACM

[8] A good overview of leakage and reduction methods are explained in the book Leakage in Nanometer CMOS Technologies ISBN 0-387-25737-3.

[9] Edwards C, “Temperature control”, Engineering & Technology 26 July - 8 August 2008, IET

[10] Patrick Moorhead (January 15, 2009). “Breaking Records with Dragons and Helium in the Las Vegas Desert”. blogs.amd. com/patmoorhead. Retrieved 2009-09-18.

[11] Prati, E.; De Michielis, M.; Belli, M.; Cocco, S.; Fanciulli, M.; Kotekar-Patil, D.; Ruoff, M.; Kern, D. P.; Wharam, D. A.; Verduijn, J.; Tettamanzi, G. C.; Rogge, S.; Roche, B.; Wacquez, R.; Jehl, X.; Vinet, M.; Sanquer, M. (2012). “Few electron limit of n-type metal oxide semiconductor single electron transistors”. Nanotechnology. 23 (21): 215204. doi:10.1088/0957-4484/23/21/215204. PMID 22552118.

9.2.9 Further reading

• Baker, R. Jacob (2010). CMOS: Circuit Design, Layout, and Simulation, Third Edition. Wiley-IEEE. p. 1174. ISBN 978-0-470-88132-3. http://CMOSedu.com

• Weste, Neil H. E.; Harris, David M. (2010). CMOS VLSI Design: A Circuits and Systems Perspective, Fourth Edition. Boston: Pearson/Addison-Wesley. p. 840. ISBN 978-0-321-54774-3. http://CMOSVLSI.com/

• Veendrick, Harry J. M. (2008). Nanometer CMOS ICs, from Basics to ASICs. New York: Springer. p. 770. ISBN 978-1-4020-8332-7.

• Mead, Carver A. and Conway, Lynn (1980). Introduction to VLSI systems. Boston: Addison-Wesley. ISBN 0-201-04358-0.

9.2.10 External links

• CMOS gate description and interactive illustrations • LASI is a “general purpose” IC layout CAD tool. It is a free download and can be used as a layout tool for CMOS circuits. 9.2. CMOS 131 Vdd Vdd

A B

Out

A

B

Vss

NAND gate in CMOS logic 132 CHAPTER 9. DAY 9

VDD

B A

OUT

VSS

METAL1 N DIFFUSION

POLY P DIFFUSION

CONTACT N-WELL

The physical layout of a NAND circuit. The larger regions of N-type diffusion and P-type diffusion are part of the transistors. The two smaller regions on the left are taps to prevent latchup. 9.2. CMOS 133 1. Grow field oxide ox.

p-type substrate 2. Etch oxide for pMOSFET ox.

p-type substrate 3. Diffuse n-well ox.

n-well p-type substrate 4. Etch oxide for nMOSFET ox.

n-well p-type substrate 5. Grow gate oxide ox.

n-well p-type substrate 6. Deposit polysilicon

ox.

n-well p-type substrate 7. Etch polysilicon and oxide ox.

n-well p-type substrate 8. Implant sources and drains ox. n+ n+ p+ p+ n-well p-type substrate 9. Grow nitride

ox. n+ n+ p+ p+ n-well p-type substrate 10. Etch nitride

ox. n+ n+ p+ p+ n-well p-type substrate 11. Deposit metal

ox. n+ n+ p+ p+ n-well p-type substrate 12. Etch metal

ox. n+ n+ p+ p+ n-well p-type substrate

Simplified process of fabrication of a CMOS inverter on p-type substrate in semiconductor microfabrication. Note: Gate, source and drain contacts are not normally in the same plane in real devices, and the diagram is not to scale. 134 CHAPTER 9. DAY 9

Cross section of two transistors in a CMOS gate, in an N-well CMOS process 9.3. ACTIVE PIXEL SENSOR 135

9.3 Active pixel sensor

An active-pixel sensor (APS) is an image sensor consisting of an integrated circuit containing an array of pixel sensors, each pixel containing a and an active amplifier. There are many types of active pixel sensors including the CMOS APS used most commonly in cell phone cameras, web cameras, most digital pocket cameras since 2010, and in most DSLRs. Such an image sensor is produced using CMOS technology (and is hence also known as a CMOS sensor), and has emerged as an alternative to charge-coupled device (CCD) image sensors.

CMOS image sensor

The term active pixel sensor is also used to refer to the individual pixel sensor itself, as opposed to the image sensor;[1] in that case the image sensor is sometimes called an active pixel sensor imager,[2] or active-pixel image sensor.[3]

9.3.1 History

The term active pixel sensor was coined in 1985 by Tsutomu Nakamura who worked on the Charge Modulation Device active pixel sensor at Olympus,[4] and more broadly defined by Eric Fossum in a 1993 paper.[5] Image sensor elements with in-pixel amplifiers were described by Noble in 1968,[6] by Chamberlain in 1969,[7] and by Weimer et al. in 1969,[8] at a time when passive-pixel sensors – that is, pixel sensors without their own amplifiers – were being investigated as a solid-state alternative to vacuum-tube imaging devices. The MOS passive-pixel sensor used just a simple switch in the pixel to read out the photodiode integrated charge.[9] Pixels were arrayed in a two- dimensional structure, with an access enable wire shared by pixels in the same row, and output wire shared by column. At the end of each column was an amplifier. Passive-pixel sensors suffered from many limitations, such as high noise, slow readout, and lack of scalability. The addition of an amplifier to each pixel addressed these problems, and resulted in the creation of the active-pixel sensor. Noble in 1968 and Chamberlain in 1969 created sensor arrays with active MOS readout amplifiers per pixel, in essentially the modern three-transistor configuration. The CCD was invented 136 CHAPTER 9. DAY 9

in October 1969 at . Because the MOS process was so variable and MOS transistors had characteristics that changed over time (Vth instability), the CCD’s charge-domain operation was more manufacturable and quickly eclipsed MOS passive and active pixel sensors. A low-resolution “mostly digital” N-channel MOSFET imager with intra-pixel amplification, for an optical mouse application, was demonstrated in 1981.[10] Another type of active pixel sensor is the hybrid infrared focal plane array (IRFPA) designed to operate at cryogenic temperatures in the infrared spectrum. The devices are two chips that are put together like a sandwich: one chip contains detector elements made in InGaAs or HgCdTe, and the other chip is typically made of silicon and is used to read out the photodetectors. The exact date of origin of these devices is classified, but by the mid-1980s they were in widespread use. By the late 1980s and early 1990s, the CMOS process was well established as a well controlled stable process and was the baseline process for almost all logic and microprocessors. There was a resurgence in the use of passive-pixel sensors for low-end imaging applications,[11] and active-pixel sensors for low-resolution high-function applications such as retina simulation[12] and high energy particle detector. However, CCDs continued to have much lower tem- poral noise and fixed-pattern noise and were the dominant technology for consumer applications such as camcorders as well as for broadcast cameras, where they were displacing video camera tubes. Eric Fossum, et al., invented the image sensor that used intra-pixel charge transfer along with an in-pixel amplifier to achieve true correlated double sampling (CDS) and low temporal noise operation, and on-chip circuits for fixed- pattern noise reduction, and published the first extensive article[5] predicting the emergence of APS imagers as the commercial successor of CCDs. Between 1993 and 1995, the Jet Propulsion Laboratory developed a number of prototype devices, which validated the key features of the technology. Though primitive, these devices demonstrated good image performance with high readout speed and low power consumption. In 1995, personnel from JPL founded Photobit Corp., who continued to develop and commercialize APS technol- ogy for a number of applications, such as web cams, high speed and motion capture cameras, digital radiography, endoscopy (pill) cameras, DSLRs and camera-phones. Many other small image sensor companies also sprang to life shortly thereafter due to the accessibility of the CMOS process and all quickly adopted the active pixel sensor approach. Most recent, the CMOS sensor technology has spread to medium-format photography with Phase One being the first to launch a medium format digital back with a Sony-built CMOS sensor.

9.3.2 Comparison to CCDs

APS pixels solve the speed and scalability issues of the passive-pixel sensor. They generally consume less power than CCDs, have less image lag, and require less specialized manufacturing facilities. Unlike CCDs, APS sensors can combine the image sensor function and image processing functions within the same integrated circuit. APS sensors have found markets in many consumer applications, especially camera phones. They have also been used in other fields including digital radiography, military ultra high speed image acquisition, security cameras, and optical mice. Manufacturers include Aptina Imaging (independent spinout from Micron Technology, who purchased Photobit in 2001), Canon, Samsung, STMicroelectronics, Toshiba, OmniVision Technologies, Sony, and Foveon, among others. CMOS-type APS sensors are typically suited to applications in which packaging, power management, and on-chip processing are important. CMOS type sensors are widely used, from high-end digital photography down to mobile- phone cameras.

Advantages of CMOS compared to CCD

A big advantage of a CMOS sensor is that it is typically less expensive than a CCD sensor. A CMOS sensor also typically has better control of blooming (that is, of bleeding of photo-charge from an over- exposed pixel into other nearby pixels).

Disadvantages of CMOS compared to CCD

Since a CMOS sensor typically captures a row at a time within approximately 1/60th or 1/50th of a second (depending on refresh rate) it may result in a "rolling shutter" effect, where the image is skewed (tilted to the left or right, depending on the direction of camera or subject movement). For example, when tracking a car moving at high speed, the car will not be distorted but the background will appear to be tilted. A frame-transfer CCD sensor does not have this problem, instead captures the entire image at once into a frame store. 9.3. ACTIVE PIXEL SENSOR 137

Blooming in a CCD image

The active circuitry in CMOS pixels takes some area on the surface which is not light-sensitive, reducing the quantum efficiency of the device. Thus, CCDs have been preferred in astronomical applications but as of the 2010s the practical advantages of CCD over CMOS appear to be disappearing.[13]

9.3.3 Architecture

Pixel

The standard CMOS APS pixel today consists of a photodetector (a pinned photodiode[14]), a floating diffusion, a transfer gate, reset gate, selection gate and source-follower readout transistor—the so-called 4T cell.[15] The pinned photodiode was originally used in interline transfer CCDs due to its low dark current and good blue response, and when coupled with the transfer gate, allows complete charge transfer from the pinned photodiode to the floating diffusion (which is further connected to the gate of the read-out transistor) eliminating lag. The use of intrapixel charge transfer can offer lower noise by enabling the use of correlated double sampling (CDS). The Noble 3T pixel is still sometimes used since the fabrication requirements are easier. The 3T pixel comprises the same elements as the 4T pixel except the transfer gate and the photodiode. The reset transistor, Mᵣ, acts as a switch to reset the floating diffusion which acts in this case as the photodiode. When the reset transistor is turned on, the photodiode is effectively connected to the power supply, VRST, clearing all integrated charge. Since the reset transistor is n-type, the pixel 138 CHAPTER 9. DAY 9

Distortion caused by a rolling shutter

operates in soft reset. The read-out transistor, M, acts as a buffer (specifically, a source follower), an amplifier which allows the pixel voltage to be observed without removing the accumulated charge. Its power supply, VDD, is typically tied to the power supply of the reset transistor. The select transistor, Mₑ, allows a single row of the pixel array to be read by the read-out electronics. Other innovations of the pixels such as 5T and 6T pixels also exist. By adding extra transistors, functions such as global shutter, as opposed to the more common rolling shutter, are possible. In order to increase the pixel densities, shared-row, four-ways and eight-ways shared read out, and other architectures can be employed. A variant of the 3T active pixel is the Foveon X3 sensor invented by Dick Merrill. In this device, three photodiodes are stacked on top of each other using planar fabrication techniques, each photodiode having its own 3T circuit. Each successive layer acts as a filter for the layer below it shifting the spectrum of absorbed light in successive layers. By deconvolving the response of each layered detector, red, green, and blue signals can be reconstructed.

APS using TFTs

For applications such as large-area digital X-ray imaging, thin-film transistors (TFTs) can also be used in APS archi- tecture. However, because of the larger size and lower transconductance gain of TFTs compared to CMOS transistors, it is necessary to have fewer on-pixel TFTs to maintain image resolution and quality at an acceptable level. A two- transistor APS/PPS architecture has been shown to be promising for APS using TFTs. In the two-transistor APS architecture on the right, TAMP is used as a switched-amplifier integrating functions of both M and Mₑ in the three-transistor APS. This results in reduced transistor counts per pixel, as well as increased pixel transconductance gain.[16] Here, Cᵢₓ is the pixel storage capacitance, and it is also used to capacitively couple the addressing pulse of the “Read” to the gate of TAMP for ON-OFF switching. Such pixel readout circuits work best with low capacitance photoconductor detectors such as amorphous selenium. 9.3. ACTIVE PIXEL SENSOR 139

A three-transistor active pixel sensor.

Array

A typical two-dimensional array of pixels is organized into rows and columns. Pixels in a given row share reset lines, so that a whole row is reset at a time. The row select lines of each pixel in a row are tied together as well. The outputs of each pixel in any given column are tied together. Since only one row is selected at a given time, no competition for the output line occurs. Further amplifier circuitry is typically on a column basis.

Size

The size of the pixel sensor is often given in height and width, but also in the optical format.

9.3.4 Design variants

Many different pixel designs have been proposed and fabricated. The standard pixel is the most common because it uses the fewest wires and the fewest, most tightly packed transistors possible for an active pixel. It is important that the active circuitry in a pixel take up as little space as possible to allow more room for the photodetector. High transistor count hurts fill factor, that is, the percentage of the pixel area that is sensitive to light. Pixel size can be traded for desirable qualities such as noise reduction or reduced image lag. Noise is a measure of the accuracy with 140 CHAPTER 9. DAY 9

A two-transistor active/passive pixel sensor

which the incident light can be measured. Lag occurs when traces of a previous frame remain in future frames, i.e. 2 the pixel is not fully reset. The voltage noise variance in a soft-reset (gate-voltage regulated) pixel√ is Vn = kT /2C , kT C/2 but image lag and fixed pattern noise may be problematic. In rms electrons, the noise is Ne = q .

Hard reset

2 Operating√ the pixel via hard reset results in a Johnson–Nyquist noise on the photodiode of Vn = kT /C or Ne = kT C q , but prevents image lag, sometimes a desirable tradeoff. One way to use hard reset is replace Mᵣ with a p-type transistor and invert the polarity of the RST signal. The presence of the p-type device reduces fill factor, as extra space is required between p- and n-devices; it also removes the possibility of using the reset transistor as an overflow anti-blooming drain, which is a commonly exploited benefit of the n-type reset FET. Another way to achieve hard reset, with the n-type FET, is to lower the voltage of VRST relative to the on-voltage of RST. This reduction may reduce headroom, or full-well charge capacity, but does not affect fill factor, unless VDD is then routed on a separate wire with its original voltage.

Combinations of hard and soft reset

Techniques such as flushed reset, pseudo-flash reset, and hard-to-soft reset combine soft and hard reset. The details of these methods differ, but the basic idea is the same. First, a hard reset is done, eliminating image lag. Next, a soft reset is done, causing a low noise reset without adding any lag.[17] Pseudo-flash reset requires separating VRST from VDD, while the other two techniques add more complicated column circuitry. Specifically, pseudo-flash reset and hard-to-soft reset both add transistors between the pixel power supplies and the actual VDD. The result is lower headroom, without affecting fill factor. 9.3. ACTIVE PIXEL SENSOR 141

Active reset

A more radical pixel design is the active-reset pixel. Active reset can result in much lower noise levels. The tradeoff is a complicated reset scheme, as well as either a much larger pixel or extra column-level circuitry.

9.3.5 See also

• Angle-sensitive pixel

• Back-illuminated sensor

• Charge-coupled device

• Planar Fourier capture array

• Oversampled binary image sensor

9.3.6 References

[1] Alexander G. Dickinson et al., “Active pixel sensor and imaging system having differential mode”, US 5631704

[2] Zimmermann, Horst (2000). Integrated Silicon Optoelectronics. Springer. ISBN 3-540-66662-1.

[3] Lawrence T. Clark, Mark A. Beiley, Eric J. Hoffman, “Sensor cell having a soft saturation circuit”US 6133563

[4] Kazuya Matsumoto et al., “A new MOS phototransistor operating in a non-destructive readout mode” Jpn. J. Appl. Phys. 24 (1985) L323

[5] Eric R. Fossum (1993), “Active Pixel Sensors: Are CCD’s Dinosaurs?" Proc. SPIE Vol. 1900, p. 2–14, Charge-Coupled Devices and Solid State Optical Sensors III, Morley M. Blouke; Ed.

[6] , (presented with an award for 'Seminal contributions to the early years of image sensors’, by the International Image sensor Society in 2015). Peter J. W. Noble (Apr 1968). “Self-Scanned Silicon Image Detector Arrays”. ED-15 (4). IEEE: 202–209.

[7] Savvas G. Chamberlain (December 1969). “Photosensitivity and Scanning of Silicon Image Detector Arrays”. IEEE Jour- nal of Solid-State Circuits. SC–4 (6): 333–342.

[8] P. K. Weimer; W. S. Pike; G. Sadasiv; F. V. Shallcross; L. Meray-Horvath (March 1969). “Multielement Self-Scanned Mosaic Sensors”. IEEE Spectrum. 6 (3): 52–65. doi:10.1109/MSPEC.1969.5214004.

[9] R. Dyck; G. Weckler (1968). “Integrated arrays of silicon photodetectors for image sensing”. IEEE Trans. Electron Devices. ED-15 (4): 196–201.

[10] Richard F. Lyon (1981). “The Optical Mouse, and an Architectural Methodology for Smart Digital Sensors”. In H. T. Kung; R. Sproull; G. Steele. CMU Conference on VLSI Structures and Computations. Pittsburgh: Computer Science Press.

[11] D. Renshaw; P. B. Denyer; G. Wang; M. Lu (1990). “ASIC image sensors”. IEEE International Symposium on Circuits and Systems 1990.

[12] M. A. Mahowald; C. Mead (12 May 1989). “The Silicon Retina”. Scientific American. 264 (5): 76–82. doi:10.1038/scientificamerican0591- 76. PMID 2052936.

[13] “Archived copy”. Archived from the original on 2016-12-23. Retrieved 2016-12-08.

[14] A review of the pinned photodiode for CCD and CMOS image sensors, IEEE J. Electron Devices Society, vol 2(3) pp. 33-43 May 2014 open access “Archived copy”. Archived from the original on 2015-10-27. Retrieved 2014-08-17.

[15] H. Lin; C.H Lai; Y. C. Ling (2004). “A four transistor CMOS active pixel sensor with high dynamic range operation”. IEEE Advanced System Integrated Circuits: 124–127.

[16] F. Taghibakhsh; k. S. Karim (2007). “Two-Transistor Active Pixel Sensor for High Resolution Large Area Digital X-Ray Imaging”. IEEE International Electron Devices Meeting: 1011–1014.

[17] IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 50, NO. 1, JANUARY 2003 142 CHAPTER 9. DAY 9

9.3.7 Further reading

• John L. Vampola (January 1993). “Chapter 5 - Readout electronics for infrared sensors”. In David L. Shu- maker. The Infrared and Electro-Optical Systems Handbook, Volume 3 - Electro-Optical Components. The International Society for Optical Engineering. ISBN 0-8194-1072-1. — one of the first books on CMOS imager array design

• Mary J. Hewitt; John L. Vampola; Stephen H. Black; Carolyn J. Nielsen (June 1994). Eric R. Fossum, ed. “Infrared readout electronics: a historical perspective”. Proceedings of SPIE. The International Society for Optical Engineering. 2226 (Infrared Readout Electronics II): 108–119. doi:10.1117/12.178474.

• Mark D. Nelson; Jerris F. Johnson; Terrence S. Lomheim (November 1991). “General noise processes in hybrid infrared focal plane arrays”. Optical Engineering. The International Society for Optical Engineering. 30 (11): 1682–1700. Bibcode:1991OptEn..30.1682N. doi:10.1117/12.55996.

• Stefano Meroli; Leonello Servoli; Daniele Passeri (June 2011). “Use of a standard CMOS imager as position detector for charged particles”. Nuclear Physics B - Proceedings Supplements. Elsevier. 215 (1): 228–231. Bibcode:2011NuPhS.215..228S. doi:10.1016/j.nuclphysbps.2011.04.016.

• Martin Vasey (September 2009). “CMOS Image Sensor Testing: An Integrated Approach”. Jova Solutions. San Francisco, CA.

9.3.8 External links

• CMOS camera as a sensor Tutorial showing how low cost CMOS camera can replace sensors in robotics appli- cations

• CMOS APS vs CCD CMOS Active Pixel Sensor Vs CCD. Performance comparison

• Image sensor inventor Peter J. W. Noble’s web page with papers and video of 2015 presentation

• Image showing FSI and BSI sensor topology

9.4 Charge-coupled device

A charge-coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by “shifting” the signals between stages within the device one at a time. CCDs move charge between capacitive bins in the device, with the shift allowing for the transfer of charge between bins. In recent years CCD has become a major technology for digital imaging. In a CCD image sensor, pixels are rep- resented by p-doped MOS . These capacitors are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. Although CCDs are not the only technology to allow for light detection, CCD image sensors are widely used in professional, medical, and scientific applications where high-quality image data are required. In applications with less exacting quality demands, such as consumer and pro- fessional digital cameras, active pixel sensors (CMOS) are generally used; the large quality advantage CCDs enjoyed early on has narrowed over time.

9.4.1 History

The charge-coupled device was invented in 1969 at AT&T Bell Labs by Willard Boyle and George E. Smith.[1] The lab was working on semiconductor bubble memory when Boyle and Smith conceived of the design of what they termed, in their notebook, “Charge 'Bubble' Devices”.[2] The device could be used as a shift register. The essence of the design was the ability to transfer charge along the surface of a semiconductor from one storage to the next. The concept was similar in principle to the bucket-brigade device (BBD), which was developed at 9.4. CHARGE-COUPLED DEVICE 143

A specially developed CCD used for ultraviolet imaging in a wire-bonded package

George E. Smith and Willard Boyle, 2009 144 CHAPTER 9. DAY 9

Research Labs during the late 1960s. The first patent (U.S. Patent 4,085,456) on the application of CCDs to imaging was assigned to Michael Tompsett.[3] The initial paper describing the concept[4] listed possible uses as a memory, a delay line, and an imaging device. The first experimental device[5] demonstrating the principle was a row of closely spaced metal squares on an oxidized silicon surface electrically accessed by wire bonds. The first working CCD made with integrated circuit technology was a simple 8-bit shift register.[6] This device had input and output circuits and was used to demonstrate its use as a shift register and as a crude eight pixel linear imaging device. Development of the device progressed at a rapid rate. By 1971, Bell researchers led by Michael Tompsett were able to capture images with simple linear devices.[7] Several companies, including Fairchild Semiconductor, RCA and Texas Instruments, picked up on the invention and began development programs. Fairchild’s effort, led by ex-Bell researcher Gil Amelio, was the first with commercial devices, and by 1974 had a linear 500-element device and a 2-D 100 x 100 pixel device. Steven Sasson, an electrical engineer working for Kodak, invented the first digital still camera using a Fairchild 100 x 100 CCD in 1975.[8] The first KH-11 KENNAN equipped with charge-coupled device array (800 x 800 pixels)[9] technology for imaging was launched in December 1976.[10] Under the leadership of Kazuo Iwama, Sony also started a large development effort on CCDs involving a significant investment. Eventually, Sony managed to mass-produce CCDs for their camcorders. Before this happened, Iwama died in August 1982; subsequently, a CCD chip was placed on his tombstone to acknowledge his contribution.[11] In January 2006, Boyle and Smith were awarded the National Academy of Engineering Charles Stark Draper Prize,[12] and in 2009 they were awarded the Nobel Prize for Physics,[13] for their invention of the CCD concept. Michael Tompsett was awarded the 2010 National Medal of Technology and Innovation for pioneering work and electronic technologies including the design and development of the first charge coupled device (CCD) imagers. He was also awarded the 2012 IEEE Edison Medal “For pioneering contributions to imaging devices including CCD Imagers, cameras and thermal imagers”.

9.4.2 Basics of operation

The charge packets (electrons, blue) are collected in potential wells (yellow) created by applying positive voltage at the gate electrodes (G). Applying positive voltage to the gate electrode in the correct sequence transfers the charge packets.

In a CCD for capturing images, there is a photoactive region (an epitaxial layer of silicon), and a transmission region made out of a shift register (the CCD, properly speaking). An image is projected through a lens onto the capacitor array (the photoactive region), causing each capacitor to accumulate an electric charge proportional to the light intensity at that location. A one-dimensional array, used in line-scan cameras, captures a single slice of the image, whereas a two-dimensional array, used in video and still cameras, captures a two-dimensional picture corresponding to the scene projected onto the focal plane of the sensor. 9.4. CHARGE-COUPLED DEVICE 145

Once the array has been exposed to the image, a control circuit causes each capacitor to transfer its contents to its neighbor (operating as a shift register). The last capacitor in the array dumps its charge into a charge amplifier, which converts the charge into a voltage. By repeating this process, the controlling circuit converts the entire contents of the array in the semiconductor to a sequence of voltages. In a digital device, these voltages are then sampled, digitized, and usually stored in memory; in an analog device (such as an analog video camera), they are processed into a continuous analog signal (e.g. by feeding the output of the charge amplifier into a low-pass filter), which is then processed and fed out to other circuits for transmission, recording, or other processing.[14]

“One-dimensional” CCD image sensor from a fax machine

9.4.3 Detailed physics of operation

Charge generation

Before the MOS capacitors are exposed to light, they are biased into the depletion region; in n-channel CCDs, the silicon under the bias gate is slightly p-doped or intrinsic. The gate is then biased at a positive potential, above the threshold for strong inversion, which will eventually result in the creation of a n channel below the gate as in a MOSFET. However, it takes time to reach this thermal equilibrium: up to hours in high-end scientific cameras cooled at low temperature.[15] Initially after biasing, the holes are pushed far into the substrate, and no mobile electrons are at or near the surface; the CCD thus operates in a non-equilibrium state called deep depletion.[16] Then, when electron– hole pairs are generated in the depletion region, they are separated by the electric field, the electrons move toward the surface, and the holes move toward the substrate. Four pair-generation processes can be identified:

• photo-generation (up to 95% of quantum efficiency),

• generation in the depletion region,

• generation at the surface, and

• generation in the neutral bulk.

The last three processes are known as dark-current generation, and add noise to the image; they can limit the total usable integration time. The accumulation of electrons at or near the surface can proceed either until image integration is over and charge begins to be transferred, or thermal equilibrium is reached. In this case, the well is said to be full. The maximum capacity of each well is known as the well depth,[17] typically about 105 electrons per pixel.[16]

Design and manufacturing

The photoactive region of a CCD is, generally, an epitaxial layer of silicon. It is lightly p doped (usually with boron) and is grown upon a substrate material, often p++. In buried-channel devices, the type of design utilized in most modern CCDs, certain areas of the surface of the silicon are ion implanted with phosphorus, giving them an n-doped designation. This region defines the channel in which the photogenerated charge packets will travel. Simon Sze details the advantages of a buried-channel device:[16] 146 CHAPTER 9. DAY 9

This thin layer (= 0.2–0.3 micron) is fully depleted and the accumulated photogenerated charge is kept away from the surface. This structure has the advantages of higher transfer efficiency and lower dark current, from reduced surface recombination. The penalty is smaller charge capacity, by a factor of 2–3 compared to the surface-channel CCD.

The gate oxide, i.e. the capacitor dielectric, is grown on top of the epitaxial layer and substrate. Later in the process, polysilicon gates are deposited by chemical vapor deposition, patterned with photolithography, and etched in such a way that the separately phased gates lie perpendicular to the channels. The channels are further defined by utilization of the LOCOS process to produce the channel stop region. Channel stops are thermally grown oxides that serve to isolate the charge packets in one column from those in another. These channel stops are produced before the polysilicon gates are, as the LOCOS process utilizes a high-temperature step that would destroy the gate material. The channel stops are parallel to, and exclusive of, the channel, or “charge carrying”, regions. Channel stops often have a p+ doped region underlying them, providing a further barrier to the electrons in the charge packets (this discussion of the physics of CCD devices assumes an electron transfer device, though hole transfer is possible). The clocking of the gates, alternately high and low, will forward and reverse bias the diode that is provided by the buried channel (n-doped) and the epitaxial layer (p-doped). This will cause the CCD to deplete, near the p–n junction and will collect and move the charge packets beneath the gates—and within the channels—of the device. CCD manufacturing and operation can be optimized for different uses. The above process describes a frame transfer CCD. While CCDs may be manufactured on a heavily doped p++ wafer it is also possible to manufacture a device inside p-wells that have been placed on an n-wafer. This second method, reportedly, reduces smear, dark current, and infrared and red response. This method of manufacture is used in the construction of interline-transfer devices. Another version of CCD is called a peristaltic CCD. In a peristaltic charge-coupled device, the charge-packet transfer operation is analogous to the peristaltic contraction and dilation of the digestive system. The peristaltic CCD has an additional implant that keeps the charge away from the silicon/silicon dioxide interface and generates a large lateral electric field from one gate to the next. This provides an additional driving force to aid in transfer of the charge packets.

9.4.4 Architecture

The CCD image sensors can be implemented in several different architectures. The most common are full-frame, frame-transfer, and interline. The distinguishing characteristic of each of these architectures is their approach to the problem of shuttering. In a full-frame device, all of the image area is active, and there is no electronic shutter. A mechanical shutter must be added to this type of sensor or the image smears as the device is clocked or read out. With a frame-transfer CCD, half of the silicon area is covered by an opaque mask (typically aluminum). The image can be quickly transferred from the image area to the opaque area or storage region with acceptable smear of a few percent. That image can then be read out slowly from the storage region while a new image is integrating or exposing in the active area. Frame-transfer devices typically do not require a mechanical shutter and were a common architecture for early solid-state broadcast cameras. The downside to the frame-transfer architecture is that it requires twice the silicon real estate of an equivalent full-frame device; hence, it costs roughly twice as much. The interline architecture extends this concept one step further and masks every other column of the image sensor for storage. In this device, only one pixel shift has to occur to transfer from image area to storage area; thus, shutter times can be less than a microsecond and smear is essentially eliminated. The advantage is not free, however, as the imaging area is now covered by opaque strips dropping the fill factor to approximately 50 percent and the effec- tive quantum efficiency by an equivalent amount. Modern designs have addressed this deleterious characteristic by adding microlenses on the surface of the device to direct light away from the opaque regions and on the active area. Microlenses can bring the fill factor back up to 90 percent or more depending on pixel size and the overall system’s optical design. The choice of architecture comes down to one of utility. If the application cannot tolerate an expensive, failure-prone, power-intensive mechanical shutter, an interline device is the right choice. Consumer snap-shot cameras have used interline devices. On the other hand, for those applications that require the best possible light collection and issues of 9.4. CHARGE-COUPLED DEVICE 147

CCD from a 2.1 megapixel Argus digital camera

CCD Sony ICX493AQA 10.14 (Gross 10.75) Mpixels APS-C 1.8” (23.98 x 16.41mm) sensor side 148 CHAPTER 9. DAY 9

CCD Sony ICX493AQA 10.14 (Gross 10.75) Mpixels APS-C 1.8” (23.98 x 16.41mm) pins side money, power and time are less important, the full-frame device is the right choice. Astronomers tend to prefer full- frame devices. The frame-transfer falls in between and was a common choice before the fill-factor issue of interline devices was addressed. Today, frame-transfer is usually chosen when an interline architecture is not available, such as in a back-illuminated device. CCDs containing grids of pixels are used in digital cameras, optical scanners, and video cameras as light-sensing devices. They commonly respond to 70 percent of the incident light (meaning a quantum efficiency of about 70 percent) making them far more efficient than photographic film, which captures only about 2 percent of the incident light. Most common types of CCDs are sensitive to near-infrared light, which allows , night-vision devices, and zero lux (or near zero lux) video-recording/photography. For normal silicon-based detectors, the sensi- tivity is limited to 1.1 μm. One other consequence of their sensitivity to infrared is that infrared from remote controls often appears on CCD-based digital cameras or camcorders if they do not have infrared blockers. Cooling reduces the array’s dark current, improving the sensitivity of the CCD to low light intensities, even for ultraviolet and visible wavelengths. Professional observatories often cool their detectors with liquid nitrogen to reduce the dark current, and therefore the thermal noise, to negligible levels.

Frame transfer CCD

The frame transfer CCD imager was the first imaging structure proposed for CCD Imaging by Michael Tompsett at Bell Laboratories. A frame transfer CCD is a specialized CCD, often used in astronomy and some professional video cameras, designed for high exposure efficiency and correctness. The normal functioning of a CCD, astronomical or otherwise, can be divided into two phases: exposure and readout. 9.4. CHARGE-COUPLED DEVICE 149

CCD from a 2.1 megapixel Hewlett-Packard digital camera

During the first phase, the CCD passively collects incoming photons, storing electrons in its cells. After the exposure time is passed, the cells are read out one line at a time. During the readout phase, cells are shifted down the entire area of the CCD. While they are shifted, they continue to collect light. Thus, if the shifting is not fast enough, errors can result from light that falls on a cell holding charge during the transfer. These errors are referred to as “vertical smear” and cause a strong light source to create a vertical line above and below its exact location. In addition, the CCD cannot be used to collect light while it is being read out. Unfortunately, a faster shifting requires a faster readout, and a faster readout can introduce errors in the cell charge measurement, leading to a higher noise level. A frame transfer CCD solves both problems: it has a shielded, not light sensitive, area containing as many cells as the area exposed to light. Typically, this area is covered by a reflective material such as aluminium. When the exposure time is up, the cells are transferred very rapidly to the hidden area. Here, safe from any incoming light, cells can be read out at any speed one deems necessary to correctly measure the cells’ charge. At the same time, the exposed part of the CCD is collecting light again, so no delay occurs between successive exposures. The disadvantage of such a CCD is the higher cost: the cell area is basically doubled, and more complex control electronics are needed. 150 CHAPTER 9. DAY 9

A frame transfer CCD sensor

Intensified charge-coupled device

Main article: Image intensifier

An intensified charge-coupled device (ICCD) is a CCD that is optically connected to an image intensifier that is mounted in front of the CCD. An image intensifier includes three functional elements: a , a micro-channel plate (MCP) and a phosphor screen. These three elements are mounted one close behind the other in the mentioned sequence. The photons which are coming from the light source fall onto the photocathode, thereby generating photoelectrons. The photoelectrons are accelerated towards the MCP by an electrical control voltage, applied between photocathode and MCP. The electrons are multiplied inside of the MCP and thereafter accelerated towards the phosphor screen. The phosphor screen finally converts the multiplied electrons back to photons which are guided to the CCD by a fiber optic or a lens. An image intensifier inherently includes a shutter functionality: If the control voltage between the photocathode and the MCP is reversed, the emitted photoelectrons are not accelerated towards the MCP but return to the photocathode. Thus, no electrons are multiplied and emitted by the MCP, no electrons are going to the phosphor screen and no light is emitted from the image intensifier. In this case no light falls onto the CCD, which means that the shutter is closed. The process of reversing the control voltage at the photocathode is called gating and therefore ICCDs are also called gateable CCD cameras. Besides the extremely high sensitivity of ICCD cameras, which enable single photon detection, the gateability is one of the major advantages of the ICCD over the EMCCD cameras. The highest performing ICCD cameras enable shutter times as short as 200 picoseconds. ICCD cameras are in general somewhat higher in price than EMCCD cameras because they need the expensive image intensifier. On the other hand, EMCCD cameras need a cooling system to cool the EMCCD chip down to temperatures around 170 K. This cooling system adds additional costs to the EMCCD camera and often yields heavy condensation problems in the application. ICCDs are used in night vision devices and in various scientific applications. 9.4. CHARGE-COUPLED DEVICE 151

Electron-multiplying CCD

image capture area

storage area

output amplifier

High voltage electron serial shift register multiplying register

Electrons are transferred serially through the gain stages making up the multiplication register of an EMCCD. The high voltages used in these serial transfers induce the creation of additional charge carriers through impact ionisation.

in an EMCCD there is a dispersion (variation) in the number of electrons output by the multiplication register for a given (fixed) number of input electrons (shown in the legend on the right). The probability distribution for the number of output electrons is plotted logarithmically on the vertical axis for a simulation of a multiplication register. Also shown are results from the empirical fit equation shown on this page.

An electron-multiplying CCD (EMCCD, also known as an L3Vision CCD, a product commercialized by e2v Ltd., GB, L3CCD or Impactron CCD, a product offered by Texas Instruments) is a charge-coupled device in which a gain register is placed between the shift register and the output amplifier. The gain register is split up into a large number of stages. In each stage, the electrons are multiplied by impact ionization in a similar way to an . The 152 CHAPTER 9. DAY 9

gain probability at every stage of the register is small (P < 2%), but as the number of elements is large (N > 500), the overall gain can be very high ( g = (1 + P )N ), with single input electrons giving many thousands of output electrons. Reading a signal from a CCD gives a noise background, typically a few electrons. In an EMCCD, this noise is superimposed on many thousands of electrons rather than a single electron; the devices’ primary advantage is thus their negligible readout noise. It is to be noted that the use of avalanche breakdown for amplification of photo charges had already been described in the U.S. Patent 3,761,744 in 1973 by George E. Smith/Bell Telephone Laboratories. EMCCDs show a similar sensitivity to intensified CCDs (ICCDs). However, as with ICCDs, the gain that is applied in the gain register is stochastic and the exact gain that has been applied to a pixel’s charge is impossible to know. At high gains (> 30), this uncertainty has the same effect on the signal-to-noise ratio (SNR) as halving the quantum efficiency (QE) with respect to operation with a gain of unity. However, at very low light levels (where the quantum efficiency is most important), it can be assumed that a pixel either contains an electron — or not. This removes the noise associated with the stochastic multiplication at the risk of counting multiple electrons in the same pixel as a single electron. To avoid multiple counts in one pixel due to coincident photons in this mode of operation, high frame rates are essential. The dispersion in the gain is shown in the graph on the right. For multiplication registers with many elements and large gains it is well modelled by the equation: ( ) − (n−m+1)m 1 − n−m+1 ≥ P (n) = − − 1 m exp g−1+ 1 if n m (m 1)!(g 1+ m ) m where P is the probability of getting n output electrons given m input electrons and a total mean multiplication register gain of g. Because of the lower costs and better resolution, EMCCDs are capable of replacing ICCDs in many applications. ICCDs still have the advantage that they can be gated very fast and thus are useful in applications like range-gated imaging. EMCCD cameras indispensably need a cooling system — using either thermoelectric cooling or liquid nitrogen — to cool the chip down to temperatures in the range of −65 to −95 °C (−85 to −139 °F). This cooling system unfortunately adds additional costs to the EMCCD imaging system and may yield condensation problems in the application. However, high-end EMCCD cameras are equipped with a permanent hermetic vacuum system confining the chip to avoid condensation issues. The low-light capabilities of EMCCDs find use in astronomy and biomedical research, among other fields. In particu- lar, their low noise at high readout speeds makes them very useful for a variety of astronomical applications involving low light sources and transient events such as lucky imaging of faint stars, high speed photon counting photome- try, Fabry-Pérot spectroscopy and high-resolution spectroscopy. More recently, these types of CCDs have broken into the field of biomedical research in low-light applications including small animal imaging, single-molecule imag- ing, Raman spectroscopy, super resolution microscopy as well as a wide variety of modern fluorescence microscopy techniques thanks to greater SNR in low-light conditions in comparison with traditional CCDs and ICCDs. In terms of noise, commercial EMCCD cameras typically have clock-induced charge (CIC) and dark current (de- pendent on the extent of cooling) that together lead to an effective readout noise ranging from 0.01 to 1 electrons per pixel read. However, recent improvements in EMCCD technology have led to a new generation of cameras ca- pable of producing significantly less CIC, higher charge transfer efficiency and an EM gain 5 times higher than what was previously available. These advances in low-light detection lead to an effective total background noise of 0.001 electrons per pixel read, a noise floor unmatched by any other low-light imaging device.[18]

9.4.5 Use in astronomy

Due to the high quantum efficiencies of CCDs (for a quantum efficiency of 100%, one count equals one photon), linearity of their outputs, ease of use compared to photographic plates, and a variety of other reasons, CCDs were very rapidly adopted by astronomers for nearly all UV-to-infrared applications. Thermal noise and cosmic rays may alter the pixels in the CCD array. To counter such effects, astronomers take several exposures with the CCD shutter closed and opened. The average of images taken with the shutter closed is necessary to lower the random noise. Once developed, the dark frame average image is then subtracted from the open-shutter image to remove the dark current and other systematic defects (dead pixels, hot pixels, etc.) in the CCD. The Hubble Space Telescope, in particular, has a highly developed series of steps (“data reduction pipeline”) to convert the raw CCD data to useful images.[19] CCD cameras used in often require sturdy mounts to cope with vibrations from wind and other sources, along with the tremendous weight of most imaging platforms. To take long exposures of galaxies and nebulae, many astronomers use a technique known as auto-guiding. Most autoguiders use a second CCD chip to monitor 9.4. CHARGE-COUPLED DEVICE 153 deviations during imaging. This chip can rapidly detect errors in tracking and command the mount motors to correct for them.

Array of 30 CCDs used on Sloan Digital Sky Survey telescope imaging camera, an example of “drift-scanning”.

An unusual astronomical application of CCDs, called drift-scanning, uses a CCD to make a fixed telescope behave like a tracking telescope and follow the motion of the sky. The charges in the CCD are transferred and read in a direction parallel to the motion of the sky, and at the same speed. In this way, the telescope can image a larger region 154 CHAPTER 9. DAY 9 of the sky than its normal field of view. The Sloan Digital Sky Survey is the most famous example of this, using the technique to produce the largest uniform survey of the sky yet accomplished. In addition to imagers, CCDs are also used in astronomical analytical instrumentation such as spectrometers.

9.4.6 Color cameras

A Bayer filter on a CCD

Digital color cameras generally use a Bayer mask over the CCD. Each square of four pixels has one filtered red, one blue, and two green (the human eye is more sensitive to green than either red or blue). The result of this is that luminance information is collected at every pixel, but the color resolution is lower than the luminance resolution. Better color separation can be reached by three-CCD devices (3CCD) and a dichroic prism, that splits the image into red, green and blue components. Each of the three CCDs is arranged to respond to a particular color. Many professional video camcorders, and some semi-professional camcorders, use this technique, although developments in competing CMOS technology have made CMOS sensors, both with beam-splitters and bayer filters, increasingly popular in high-end video and digital cinema cameras. Another advantage of 3CCD over a Bayer mask device is higher quantum efficiency (and therefore higher light sensitivity for a given aperture size). This is because in a 3CCD device most of the light entering the aperture is captured by a sensor, while a Bayer mask absorbs a high proportion (about 2/3) of the light falling on each CCD pixel. For still scenes, for instance in microscopy, the resolution of a Bayer mask device can be enhanced by microscanning technology. During the process of color co-site sampling, several frames of the scene are produced. Between ac- quisitions, the sensor is moved in pixel dimensions, so that each point in the visual field is acquired consecutively by elements of the mask that are sensitive to the red, green and blue components of its color. Eventually every pixel in the image has been scanned at least once in each color and the resolution of the three channels become equivalent (the resolutions of red and blue channels are quadrupled while the green channel is doubled).

Sensor sizes

Main article: Image sensor format 9.4. CHARGE-COUPLED DEVICE 155

Sony 2/3” CCD ICX024AK 10A 494496 (816*606) pixels CCD removed from video camera Sony CCD-V88E from 1988 year with vertical stripe filter Yellow, Green and Cyan

CCD color sensor

Sensors (CCD / CMOS) come in various sizes, or image sensor formats. These sizes are often referred to with an inch fraction designation such as 1/1.8″ or 2/3″ called the optical format. This measurement actually originates back 156 CHAPTER 9. DAY 9

x80 microscope view of an RGGB Bayer filter on a 240 line Sony CCD PAL Camcorder CCD sensor in the 1950s and the time of Vidicon tubes.

9.4.7 Blooming

When a CCD exposure is long enough, eventually the electrons that collect in the “bins” in the brightest part of the image will overflow the bin, resulting in blooming. The structure of the CCD allows the electrons to flow more easily in one direction than another, resulting in vertical streaking.[20][21][22] Some anti-blooming features that can be built into a CCD reduce its sensitivity to light by using some of the pixel area for a drain structure.[23] James M. Early developed a vertical anti-blooming drain that would not detract from the light collection area, and so did not reduce light sensitivity.

9.4.8 See also

• Photodiode • CMOS sensor • Angle-sensitive pixel • Rotating line camera • Superconducting camera • Wide dynamic range • Hole accumulation diode (HAD) • Andor Technology – Manufacturer of EMCCD cameras 9.4. CHARGE-COUPLED DEVICE 157

Vertical smear

• Photometrics - Manufacturer of EMCCD cameras

• QImaging - Manufacturer of EMCCD cameras

• PI/Acton – Manufacturer of EMCCD cameras

• Stanford Computer Optics – Manufacturer of ICCD cameras

• Time delay and integration (TDI)

• Glossary of video terms

9.4.9 References

[1] See U.S. Patent 3,792,322 and U.S. Patent 3,796,927

[2] James R. Janesick (2001). Scientific charge-coupled devices. SPIE Press. p. 4. ISBN 978-0-8194-3698-6.

[3] U.S. Patent 4,085,456

[4] W. S. Boyle; G. E. Smith (April 1970). “Charge Coupled Semiconductor Devices”. Bell Syst. Tech. J. 49 (4): 587–593.

[5] G. F. Amelio; M. F. Tompsett; G. E. Smith (April 1970). “Experimental Verification of the Charge Coupled Device Concept”. Bell Syst. Tech. J. 49 (4): 593–600.

[6] M. F. Tompsett; G. F. Amelio; G. E. Smith (1 August 1970). “Charge Coupled 8-bit Shift Register”. Applied Physics Letters. 17: 111–115. Bibcode:1970ApPhL..17..111T. doi:10.1063/1.1653327.

[7] Tompsett, M.F.; Amelio, G.F.; Bertram, W.J., Jr.; Buckley, R.R.; McNamara, W.J.; Mikkelsen, J.C., Jr.; Sealer, D.A. (November 1971). “Charge-coupled imaging devices: Experimental results”. IEEE Transactions on Electron Devices. 18 (11): 992–996. doi:10.1109/T-ED.1971.17321. ISSN 0018-9383.

[8] Dobbin, Ben. (2005-09-08) Kodak engineer had revolutionary idea: the first digital camera. seattlepi.com. Retrieved on 2011-11-15.

[9] globalsecurity.org - KH-11 KENNAN, 2007-04-24

[10] “NRO review and redaction guide (2006 ed.)" (PDF). National Reconnaissance Office. 158 CHAPTER 9. DAY 9

[11] Johnstone, B. (1999). We Were Burning: Japanese Entrepreneurs and the Forging of the Electronic Age. New York: Basic Books. ISBN 0-465-09117-2.

[12] “Charles Stark Draper Award”.

[13] “Nobel Prize website”.

[14] Gilbert F. Amelio (February 1974). “Charge-Coupled Devices”. Scientific American. 230 (2).

[15] For instance, the specsheet of PI/Acton’s SPEC-10 camera specifies a dark current of 0.3 electron per pixel per hour at −110 °C.

[16] Sze, S. M.; Ng, Kwok K. (2007). Physics of semiconductor devices (3 ed.). John Wiley and Sons. ISBN 978-0-471-14323- 9. Chapter 13.6.

[17] Apogee CCD University - Pixel Binning

[18] Daigle, Olivier; Djazovski, Oleg; Laurin, Denis; Doyon, René; Artigau, Étienne (July 2012). “Characterization results of EMCCDs for extreme low light imaging” (PDF).

[19] Hainaut, Oliver R. (December 2006). “Basic CCD image processing”. Retrieved January 15, 2011. Hainaut, Oliver R. (June 1, 2005). “Signal, Noise and Detection”. Retrieved October 7, 2009. Hainaut, Oliver R. (May 20, 2009). “Retouching of astronomical data for the production of outreach images”. Retrieved October 7, 2009. (Hainaut is an astronomer at the European Southern Observatory)

[20] Phil Plait. “The Planet X Saga: SOHO Images”

[21] Phil Plait. “Why, King Triton, how nice to see you!"

[22] Thomas J. Fellers and Michael W. Davidson. “CCD Saturation and Blooming” Archived July 27, 2012, at the Wayback Machine.

[23] Albert J. P. Theuwissen (1995). Solid-State Imaging With Charge-Coupled Devices. Springer. pp. 177–180. ISBN 9780792334569.

9.4.10 External links

• Journal Article On Basics of CCDs

• Nikon microscopy introduction to CCDs

• Concepts in Digital Imaging Technology

• More statistical properties

• L3CCDs used in astronomy

9.5 Shutter (photography)

In photography, a shutter is a device that allows light to pass for a determined period, exposing photographic film or a light-sensitive electronic sensor to light in order to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as seen in a or a signal lamp. A shutter of variable speed is used to control exposure time of the film. The shutter is so constructed that it automatically closes after a certain required time interval. The speed of the shutter is controlled by a ring outside the camera, on which various timings are marked. 9.5. SHUTTER (PHOTOGRAPHY) 159

9.5.1 Camera shutter

Camera shutters can be fitted in several positions:

• Leaf shutters are usually fitted within a lens assembly (central shutter), or more rarely immediately behind (behind-the-lens shutter) or, even more rarely, in front of a lens, and shut off the beam of light where it is narrow. • Focal-plane shutters are mounted near the focal plane and move to uncover the film or sensor.

Behind-the-lens shutters were used in some cameras with limited lens interchangeability. Shutters in front of the lens, sometimes simply a lens cap that is removed and replaced for the long exposures required, were used in the early days of photography. Other mechanisms than the dilating aperture and the sliding curtains have been used; anything which exposes the film to light for a specified time will suffice. The time for which a shutter remains open (exposure time, often called “shutter speed”) is determined by a timing mechanism. These were originally pneumatic (Compound shutter) or clockwork, but since the late twentieth century are mostly electronic. Mechanical shutters typically had a Time setting, where the shutter opened when the button was pressed and remained open until it was pressed again, where the shutter remained open as long as the button was pressed (originally actuated by squeezing an actual rubber bulb), and Instantaneous exposure, with settings ranging from 30” to 1/4000” for the best leaf shutters, faster for focal-plane shutters, and more restricted for basic types. The reciprocal of exposure time in seconds is often used for engraving shutter settings. For example, a marking of “250” denotes 1/250”. This does not cause confusion in practice. The exposure time and the effective aperture of the lens must together be such as to allow the right amount of light to reach the film or sensor. Additionally, the exposure time must be suitable to handle any motion of the subject. Usually it must be fast enough to “freeze” rapid motion, unless a controlled degree of motion blur is desired, for example to give a sensation of movement. Most shutters have a flash synchronization switch to trigger a flash, if connected. This was quite a complicated matter with mechanical shutters and flashbulbs which took an appreciable time to reach full brightness, focal-plane shutters making this even more difficult. Special flashbulbs were designed which had a prolonged burn, illuminating the scene for the whole time taken by a focal plane shutter slit to move across the film. These problems were essentially solved for non-focal-plane shutters with the advent of electronic flash units which fire virtually instantaneously and emit a very short flash. When using a focal-plane shutter with a flash, if the shutter is set at its X-sync speed or slower the whole frame will be exposed when the flash fires (otherwise only a band of the film will be exposed). Some electronic flashes can produce a longer pulse compatible with a focal-plane shutter operated at much higher shutter speeds. The focal-plane shutter will still impart focal-plane shutter distortions to a rapidly moving subject. Cinematography uses a rotary disc shutter in movie cameras, a continuously spinning disc which conceals the image with a reflex mirror during the intermittent motion between frame exposure. The disc then spins to an open section that exposes the next frame of film while it is held by the registration pin.

Focal-plane shutter

Main article: Focal-plane shutter

A focal-plane shutter is positioned just in front of the film, in the focal plane, and moves an aperture across the film until the full frame has been exposed. Focal-plane shutters are usually implemented as a pair of light-tight cloth, metal, or plastic curtains. For shutter speeds slower than a certain point (known as the X-sync speed of the shutter), which depends on the camera, one curtain of the shutter opens, and the other closes after the correct exposure time. At shutter speeds faster than the X-sync speed, the top curtain of the shutter travels across the focal plane, with the second curtain following behind, effectively moving a slit across the focal plane until each part of the film or sensor has been exposed for the correct time. The effective exposure time can be much shorter than for central shutters, at the cost of some distortion of fast-moving subjects. Focal plane shutters have the advantage over central leaf shutters of allowing the use of interchangeable lenses without requiring a separate shutter for each lens. (Leaf shutters behind the lens also allow interchanging the lens using a single shutter.) 160 CHAPTER 9. DAY 9

They have several disadvantages as well:

• Distortion of fast-moving subjects: although no part of the film is exposed for longer than the time set on the dial, one edge of the film is exposed an appreciable time after the other, so that a horizontally moving shutter will, for example, elongate or shorten the image of a car speeding in the same or the opposite direction to the shutter movement.

• They are noisier, which is a detriment to candid and nature photography.

• Their more complex mechanical structure causes a shorter life-span than other shutter designs.

• If a focal-plane shutter camera is left with sunlight falling on the lens (and the mirror up for an SLR), it is possible to burn a hole in the closed curtain of a non-metal shutter.

• Camera shake due to the impact of the larger curtains starting and stopping rapidly. Camera designers have learned to overcome SLR mirror-slap by including a mirror lock-up feature in some cameras. This removes the camera-shake from the large slapping mirror inside the camera, but does not prevent camera-shake caused by the shutter mechanism itself. Mirror-lock-up introduces yet another problem: with the mirror locked-up out of the way the optical viewfinder cannot be used for focussing, framing, or exposure metering. Newer DSLR cameras include a "live preview" where the image from the main imaging sensor is displayed directly on an LCD display, so it is still possible to focus (manually or in newer models by contrast detection) and frame. This prevents most camera shake from the focal-plane shutter, as instead of a first curtain an electronic shutter is used.

Simple leaf shutter

A simple leaf shutter is a type of camera shutter consisting of a mechanism with one or more pivoting metal leaves which normally does not allow light through the lens onto the film, but which when triggered opens the shutter by moving the leaves to uncover the lens for the required time to make an exposure, then shuts. Simple leaf shutters have a single leaf, or two leaves, which pivot so as to allow light through to the lens when triggered. If two leaves are used they have curved edges to create a roughly circular aperture. They typically have only one shutter speed and are commonly found in basic cameras, including disposable cameras. Some have more than one speed. Shutters for newer digital cameras are a combination of electronic and mechanical timings. Some cameras employ a 100% electronic shutter, created by turning on and off the imaging sensor’s signals. Digital cameras that can also take video implement this method for their video modes. For single-frame photography then either mechanical or mechanical and electronic methods are used.

Diaphragm shutter

A diaphragm or leaf[1] shutter (as distinct from the simple leaf shutter above) consists of a number of thin blades which briefly uncover the camera aperture to make the exposure. The blades slide over each other in a way which creates a circular aperture which enlarges as quickly as possible to uncover the whole lens, stays open for the required time, then closes in the same way.[2] The larger the number of blades, the more accurately circular is the aperture. is easily achieved with a pair of contacts that close when the shutter is fully open. Ideally the shutter opens instantaneously, remains open as long as required, and closes instantaneously. This is es- sentially the case at slower speeds, but as speeds approach their maximum the shutter is far from fully open for a significant part of the exposure time. Effectively the shutter acts as an additional aperture, and may, for example, cause vignetting or increase depth of field, undesirable if shallow focus is being used creatively. The term diaphragm shutter has also been used to describe an optical stop with a slit, near the focal plane of a moving-film high-speed camera.[3] A few types and makers of leaf shutters became very well known. The early Compound shutter had a pneumatic mechanism, with a piston sliding against air resistance in a cylinder. They were quieter at slow speeds than clockwork, but potentially very inaccurate. More accurate clockwork mechanisms then replaced the airbrake, and the German Compur,[1] and the later Synchro-Compur, became virtually the standard quality shutter. Later the Japanese Copal shutter was widely adopted in quality equipment. The German Prontor and Japanese Seikosha shutters were also 9.5. SHUTTER (PHOTOGRAPHY) 161 widely used. Up and Down with Compur: The development and photo-historical meaning of leaf shutters, by Klaus- Eckard Riess, translated by Robert Stoddard[1] gives a detailed history and technical description of leaf shutters. The company Compur Monitor was still in business as of 2012, but made only gas detection systems.[4]

Central shutter

A central shutter is not a type of shutter as such, but describes the position of the shutter: it is typically a leaf shutter (or simple leaf shutter), and located within the lens assembly where a relatively small opening allows light to cover the entire image. Leaf shutters can also be located behind, but near, the lens, allowing lens interchangeability. The alternative to a central or behind-the-lens shutter is a focal-plane shutter. Interchangeable-lens cameras with a central shutter within the lens body require that each lens has a shutter built into it. In practice most cameras with interchangeable lenses use a single focal plane shutter in the camera body for all lenses, while cameras with a fixed lens use a central shutter. Many medium-format and most large-format cameras, however, have interchangeable lenses each fitted with a central shutter. A few interchangeable-lens cameras have a behind-the-lens leaf shutter. Large-format press cameras often had a focal-plane shutter. Some had both a focal- plane shutter (for lens interchangeability) and a lens with central shutter (for flash synchronisation); one shutter would be locked open. Film cameras, but not digital cameras, with a central shutter and interchangeable lenses often have a secondary shutter or darkslide to cover the film and allow changing lens in mid-roll without fogging the film. The main advantages of central and behind-the-lens leaf shutters compared to a focal-plane shutter are:

• Flash synchronization is possible at all speeds because the shutter opens fully, unlike a focal-plane shutter sliding a slit relatively slowly across the film for a short effective exposure.

• Small size is possible as the shutter is placed where the bundle of rays is narrow, either inside or just behind the lens.

• Many versions have no connection between the cocking mechanism and the film advance mechanism, making multiple exposures possible (this can be a disadvantage if the film is not advanced due to inadvertence).

• Usually much quieter.

• More realistic photographs in high speed follow-through—lateral focal plane shutters compress or elongate the image in such cases.

• Longer shutter life.

Some disadvantages of the central shutter are:

• For an interchangeable lens system, each lens has to have a shutter built into it.

• All leaf shutter speeds are limited by the speed at which the leaves can move: typically 1/500th of a second for a high-specification diaphragm shutter and 1/125th of a second for a simple leaf shutter.

• Some versions may have no connection between the cocking mechanism and the film advance mechanism, making accidental multiple exposures a common problem, although this is a feature of camera manufacture rather than the shutter itself.

Electronic shutter

Digital image sensors (both CMOS and CCD image sensors) can be constructed to give a shutter equivalent function by transferring many pixel cell charges at one time to a paired shaded double called frame transfer shutter. If the full-frame is transferred at one time, it is a global shutter. Often the shaded cells can independently be read, while the others are again collecting light.[5] Extremely fast shutter operation is possible as there are no moving parts or any serialized data transfers. Global shutter can also be used for videos as a replacement for rotary disc shutters. Image sensors without a shaded full-frame double must use serialized data transfer of illuminated pixels called rolling shutter. A rolling shutter scans the image in a line-by-line fashion, so that different lines are exposed at different 162 CHAPTER 9. DAY 9

instants, as in a mechanical focal-plane shutter, so that motion of either camera or subject will cause geometric distortions, such as skew or wobble.[6] Today, most digital cameras use combination of mechanical shutter and electronic shutter or mechanical shutter solely. Mechanical shutter can accommodate up to 1/16000 seconds (for example the Minolta Dynax/Maxxum/α−9 film camera had a maximum of 1/12000, a record in its era, and the later digital Nikon D1 series were capable of 1/16000), while electronic shutter can accommodate at least 1/32000 seconds, used for many superzoom cameras and currently many Fujifilm APS-C cameras (X-Pro2, X-T1, X100T and others).

9.5.2 Shutter lag

Shutter lag is the time between the shutter release being pressed and the exposure started. While this delay was insignificant on most film and some digital cameras, many digital cameras have significant delay, which can be a problem with fast-moving subjects as in sports and other action photography. Release lag of a bridge camera such as the 2010 Pentax X90 is a relatively short 1/50 s,[7] or 21 milliseconds (ms). The Canon 50d dSLR is specified at 131 ms lag.[8] In many cases autofocus (AF) lag is the root cause of shutter lag. Lower-cost cameras and low-light or low-contrast situations will make the effect more pronounced and it is in these cases that AF lag is more noticed. Most AF systems use contrast to determine focus; in situations where contrast is low, the speed at which the camera can determine the best focus can be quite noticeable. Since most modern cameras will not activate the shutter until autofocus is complete, the result is shutter lag. In these cases, the photographer can switch to manual focus to avoid the delay that is attributable to the AF function.

9.5.3 Shutter cycle

A shutter cycle is the process of the shutter opening, closing, and resetting to where it is ready to open again. The life-expectancy of a mechanical shutter is often expressed as a number of shutter cycles.

9.5.4 Projector shutter

In movie projection, the shutter admits light from the lamphouse to illuminate the film across to the projection screen. To avoid flicker, a double-bladed rotary disc shutter admits light two times per frame of film. There are also some models which are triple-bladed, and thus admit light three times per frame (see Persistence of vision). Shutters are also used simply to regulate pulses of light, with no film being used, as in a signal lamp.

9.5.5 See also

• Photographic lens

• Kerr cell shutter

•

9.5.6 References

[1] Up and Down with Compur: The development and photo-historical meaning of leaf shutters, by Klaus-Eckard Riess, translated by Robert Stoddard

[2] Sidney Ray, Scientific Photography and Applied Imaging, Oxford: Focal Press, 1999

[3] Focal Encyclopedia of Photography, Macmillan, 1957

[4] Compur Monitor website (no longer a shutter manufacturer)

[5] Electronic shuttering: Rolling vs Global shutter Motionvideoproducts

[6] Shutter Operations for CCD and CMOS Image Sensors Kodak (PDF) 9.5. SHUTTER (PHOTOGRAPHY) 163

[7] http://www.adorama.com/alc/news/Pentax-unveils-X90-Megazoom-digital-camera

[8] http://snapsort.com/compare/Canon_EOS_50D-vs-Canon_EOS_60D 164 CHAPTER 9. DAY 9

The 1911 Cyclopedia of Photography divides shutters into “roller-blind” and “diaphragm” types, corresponding roughly to the modern focal-plane and leaf types. 9.5. SHUTTER (PHOTOGRAPHY) 165

A focal-plane shutter. The plastic curtains travel vertically.

5 1

2 3

4

6

Simple leaf shutter 1. Shutter plate 2. Aperture covered by leaf shutter 3. Aperture during exposure 4. Leaf blade 5. Catch mechanism 6. Butterfly spring 166 CHAPTER 9. DAY 9

One diaphragm shutter opening over another in an Akarex camera 9.5. SHUTTER (PHOTOGRAPHY) 167

Entries in Cassell’s Cyclopedia of Photography, 1911. The terminology diaphragm shutter has since fallen from common use. 168 CHAPTER 9. DAY 9

9.6 Mode dial

Generic mode dial for digital cameras showing several common modes. Actual dials may have more or fewer.

A mode dial or camera dial is a dial used on digital cameras to change the camera’s mode. Most digital cameras, including dSLR and SLR-like cameras, support modes, selectable either by a dial or from a menu. On point-and-shoot cameras which support modes a range of scene types is offered. On dSLR cameras and SLR-like cameras, mode dials usually offer access to manual settings. The more compact point-and-shoot cameras, and cameras offering a great many modes, do not have mode dials, using menus instead. Some SLR lenses themselves offer control over things such as aperture, reducing the need for mode support in the camera body.

9.6.1 Location of the dial

On most dSLRs and SLR-like bridge cameras, the mode dial is located at the top of the camera, to one side of the flash/viewfinder hump. On point-and-shoot cameras, however, the mode dial’s location is less standard. On many models, it is found on top like dSLRs. On other point-and-shoots, particularly those with a thin body, the dial is found on the back of the camera, often coupled with a menu-navigation button. Some thin cameras use a slide switch rather than a dial.

9.6.2 Modes

Main article: List of digital camera modes

Various camera types and specific cameras have different modes. The simpler dial in the top illustration has:

• Manual modes: Manual (M), Program (P), Shutter priority (S), (A). • Automatic modes: Auto, Action, Portrait, Night portrait, Landscape, Macro.

Most dSLRs have a few manual settings and a small sample of automatic modes. Most SLR-like cameras have manual modes and several automatic scene modes. On point-and-shoot cameras, all manual control may be condensed into 9.6. MODE DIAL 169

Some dials have more modes.

A Kodak dSLR with the mode dial located near the flash/viewfinder hump. 170 CHAPTER 9. DAY 9 one mode (e.g. ASP, for Aperture priority, Shutter priority, Program) or may be completely absent. Many compact cameras show a large array of scene modes. Point-and-shoot and SLR-like digital cameras usually have a movie mode to capture videos, and many modern dSLRs also support movie modes. Detailed information found by users on the modes supported by digital cameras are to be found in the ongoing list of digital camera modes.

Manual modes

Manual modes include:[1][2]

• P: Program mode offers the photographer partial control over shutter speed and aperture.

• A or Av: Aperture priority AKA Aperture value allows the photographer to control the aperture, while the shutter speed and ISO sensitivity are calculated by the camera.

• S or Tv: Shutter priority AKA “Time value” allows the photographer to control the shutter speed, while the aperture and ISO sensitivity are calculated by the camera.

• Sv Sensitivity value allows the photographer to control the ISO sensitivity, while aperture and shutter speed are calculated by the camera (this is a Pentax DSLR feature)

• M: Manual mode allows the photographer to control shutter speed, aperture and ISO independently.

• U: User mode (like program with preset)

Automatic scene modes

In automatic modes the camera determines all aspects of exposure, choosing exposure parameters according to the application within the constraints of correct exposure, including exposure, aperture, focussing, light metering, white balance, and equivalent sensitivity. For example in portrait mode the camera would use a wider aperture to render the background out of focus, and would seek out and focus on a human face rather than other image content. In the same light conditions a smaller aperture would be used for a landscape, and recognition of faces would not be enabled for focussing. Some cameras have tens of modes, showing the majority only in the menu rather than on the dial. Many cameras do not document exactly what their many modes do; for full mastery of the camera one must experiment with them. In general:

• Action or sport mode increases ISO and uses a fast shutter speed to capture action.

• Landscape mode uses a small aperture to gain depth of field.

• Portrait mode widens the aperture to throw the background out of focus. The camera may recognise and focus on a human face.

• Night portrait mode uses an exposure long enough to capture background detail, with fill-in flash to illuminate a nearby subject.

Other scene modes found on many cameras include Fireworks, Snow, Natural light/Night snapshot, Macro/Close-up, and Movie mode.

9.6.3 See also

• List of digital camera modes

• Shutter priority

• Aperture priority 9.7. DIGITAL CAMERA MODES 171

• Digital ISO sensitivity

• Digital camera

• Digital SLR

9.6.4 References

[1] “Pentax K-5 user manual” (PDF). 1 January 2012. Retrieved 1 January 2012.

[2] “Nikon D300s user manual” (PDF). 1 January 2012. Retrieved 1 January 2012.

9.7 Digital camera modes

Generic mode dial for digital cameras showing some of the most common modes. (Actual mode dials can vary; for example point- and-shoot cameras seldom have manual modes.) Manual modes: Manual (M), Program (P), Shutter priority (S), Aperture priority (A). Automatic modes: Auto, Action, Portrait, Night portrait, Landscape, Macro.

Most digital cameras support a number of digital camera modes for use in various situations. Professional DSLR cameras modes focus more on manual modes, consumer point-and-shoot cameras focus on automatic modes, and amateur prosumer cameras often have a wide variety of both manual and automatic modes.

9.7.1 Manual-enabled modes

Manual-enabled modes give the photographer control over the various parameters of an exposure. There are three exposure parameters – aperture, time (shutter speed), and sensitivity (ISO), and in different modes these are each set automatically or manually; this gives 23 = 8 possible modes. For a given exposure, this is an underdetermined system, as there are three inputs but only one output. Accordingly, there are many combinations that result in the same exposure – for example, decreasing the aperture by one stop but increasing the exposure time or sensitivity to compensate, and there are various possible algorithms to automatically choose between these. 172 CHAPTER 9. DAY 9

A dial with more modes

Most often, ISO is considered separately, being either set manually or set to Auto ISO, and then only aperture and shutter speed need be determined – either determines the other. The four main modes, sometimes abbreviated “PASM”, are:

• P: Program mode has the camera calculate both shutter speed and aperture (given a manually or automatically selected ISO). Higher-end cameras offer partial manual control to shift away from the automatically calculated values (increasing aperture and decreasing shutter time or conversely). The difference between Program mode and Full Auto mode is that in program mode, only the exposure is automatic, while other camera settings (e.g. shooting mode, , flash) can be set manually; in Full Auto mode everything is automatic.

• A or Av: Aperture priority or 'Aperture value' enables manual control of the aperture, and shutter speed is calculated by the camera for proper exposure (given an ISO sensitivity).

• S or Tv: Shutter priority or 'Time value' enables manual control of the shutter speed, and aperture is calculated by the camera for proper exposure (given an ISO sensitivity).

• M: Manual mode both shutter speed and aperture and independently set manually (with ISO sensitivity also set manually), where proper image exposure requires accurate manual adjustment.

Together with setting ISO manually or automatically, this (PASM) yields the 4×2 = 8 possible combinations of manual/auto. Exposure is further controlled in each of the above modes with an independent setting for:

• Ev: '', which enables an increase/decrease in image exposure compensation to make the result- ing image brighter/darker, typically selectable in steps of whole or partial exposure “stops” (discrete widen- ing/tightening of the aperture). Many cameras offer “exposure bracketing” where sequential images will be exposed at the different compensations selected, so as to increase the probability of a perfectly exposed image. 9.7. DIGITAL CAMERA MODES 173

Less commonly seen modes include:

• Sv: Sensitivity priority or “ISO priority” controls the Sensitivity value (ISO speed), with both shutter and aperture calculated by camera, similar to Program mode. This mode is found on some ; on many cameras (such as Canon and Nikon) this is not a separate mode, but instead is accomplished by using Program mode and manually selecting an ISO. • TAv: Some Pentax cameras such as Pentax K-50 has this mode for rapidly changing lights by using the widest aperture and the lowest ISO of continuously changing ISO between 1,000 to 3,200.[1][2] The range of contin- uously changing ISO is dependent on the camera manufacture. Other manufacturers may provide this func- tionality through automatic selection of ISO speed in manual mode. • DEP:[3] In DEP (DEPth of field) mode, seen on some Canon cameras, the aperture is set to yield the desired depth of field: one points at the nearest object that one wants to be in focus, half-presses the shutter, then points at the farthest object that one wants to be in focus, half-presses the shutter, at which point the camera sets both focus and aperture so that both objects are in focus. One then reframes the scene and fully depresses the shutter to take the photo. Unlike other modes, this also sets focus, and requires two separate metering/focus stages. • A-DEP:[3] Canon also offers A-DEP (Automatic DEPth of field) mode on some cameras, which sets the depth of field and focus in a single shot. However, this requires lining up both the nearest and further objects on autofocus points at the same time, which may be difficult.

In cases where there is camera discretion (e.g., Auto ISO), different cameras allow different configuration of how decisions are made. For example, As of 2008, Nikon cameras allow one to set the maximum and minimum ISO sensitivities, and slowest shutter speed that will be used in automatic modes,[4] while Canon cameras will select within the fixed range of ISO 400–ISO 800 in Auto ISO mode. In Nikon cameras, the Auto ISO mode first adjusts the shutter speed, keeping ISO at its minimum desired value, then, when shutter speed reaches the user-defined limit, the ISO is increased, up to the maximum value.[5] All of the above functions are independent of lens focus and stabilizing methods.

9.7.2 Automatic modes

In automatic modes the camera determines all aspects of exposure, choosing exposure parameters according to the application within the constraints of correct exposure, including exposure, aperture, focusing, light metering, white balance, and equivalent sensitivity. For example in portrait mode the camera would use a wider aperture to render the background out of focus, and would seek out and focus on a human face rather than other image content. In the same light conditions a smaller aperture would be used for a landscape, and recognition of faces would not be enabled for focusing. Some cameras have tens of modes. Many cameras do not document exactly what their many modes do; for full mastery of the camera one must experiment with them. In general:

• Action or sports modes increase ISO and uses a faster shutter speed to capture action. • Landscape modes use a small aperture to gain depth of field. Flash may be deactivated. • Text mode increases in-camera sharpening to allow to photograph texts. • Portrait mode widens the aperture to throw the background out of focus. The camera may recognize and focus on a human face. • Night portrait modes uses an exposure long enough to capture background detail, with fill-in flash to illuminate a nearby subject. • Fireworks modes, for use on a tripod, use an extended exposure (around four seconds) which results in showing several fireworks as well as their paths. • Water modes, depending on what the mode is designed to do, will either widen the aperture and increase the shutter speed for an action shot or shrink the aperture and slow down the shutter speed to show the motion of the water. 174 CHAPTER 9. DAY 9

• Snow modes compensate for the misinformation the white snow gives the light meter and increases exposure in order to properly photograph subjects.

• Natural light or night snapshot modes attempt to raise the ISO and use a very wide aperture in order to take a photograph using the limited natural light, rather than a flash. In Fujifilm cameras, a variation of this mode takes two pictures: one with flash and other without it.

• High-sensitivity modes use the highest ISO available, albeit at lower resolutions in order to cope with noise.

• Macro or close-up modes tend to direct the camera’s focus to be nearer the camera. They may shrink the aperture and restrict the camera to wide-angle in an attempt to broaden the depth-of-field (to include closer objects) – this last mode of operation is often known as Super Macro.

• Movie mode allows a still camera to take moving pictures.

• 'Scene' or Smart Shutter (SCN) mode (on Canons) which uses face detection to take a picture either when a subject smiles, winks or when a new subject enters the scene.

• Sunset modes enhance warm colors, such as those that can be found on sunsets.

• Dusk/Dawn mode, found on Nikon compacts, enhance the blue colors of twilights and dawns, as well as raise the ISO to compensate for the low levels of light present then.

• Beach modes enhance blue colors such as those of the sea and sky as well as prevent underexposure because of strong sunlight.

• Starry sky mode, on Panasonic compact and bridge cameras, gives a long shutter speed (up to 60 seconds) to capture star trails as well as other subjects that require very long exposures.

• Foliage mode, present on Canon cameras, enhances green colors of vegetation.

This list is incomplete; you can help by expanding it.

9.7.3 Secondary modes

Aside from the main modes which control exposure, there are usually other, secondary settings common to digital cameras; examples follow.

Shooting modes

Shooting modes – “Burst” or “rapid fire” mode will take a number of photographs in quick succession, often used when a photograph of a specific instance is needed (e.g. the end of a race), while “Single” mode will take a single picture each time the shutter is depressed.

Autofocus modes

Autofocus modes – autofocus can either activate until a lock is found (single, AF-S) or be continuously active (con- tinuous, AF-C, servo). Single mode is especially used for stationary subjects, when focus, once found, should stay fixed, while continuous mode is instead used for moving subjects. Some AF systems also include anticipation of position of moving subjects – Canon calls this "AI servo" (for "artificial intelligence") – or can automatically switch between single and continuous depending on whether the subject is moving – Canon calls this “AI focus”. A separate but often related distinction is between focus priority and release priority – whether the camera will take a picture when the subject is out of focus or not. In focus priority, the camera will only take a picture when the subject is in focus (as detected by the AF system), while in release priority, the camera will take a picture whenever the shutter is pressed.[6] Release priority is particularly used of fast-moving subjects, which may not be perfectly in focus, or by experienced photographers, who wish to override the camera’s judgment of whether the scene is in focus. 9.8. SHUTTER PRIORITY 175

These are usually combined – for stationary subjects, AF is set to single (lock when found) and release is set to focus priority, while for moving subjects, AF is set to continuous and release is set to release priority. Manual focus is generally in release priority – AF is neither detected nor set. Note that these “priority” modes should not be confused with the same word in exposure modes. Focus priority can also be used for the trap focus trick, to take a picture only when a subject hits a focus point, by using AF to detect focus but not set it.

Flash

Flash modes allow the user to choose between common settings such as "Fill flash" to always use flash, “Auto flash” which will use flash in low-lit areas, “Red-eye reduction” which may flash once before the actual photo in order to shrink the subject’s pupils and reduce red-eye, or “Flash off” which will never use flash. Flash can have its own exposure compensation – how brightly it flashes – which allows one to independently adjust the exposure of the foreground (lit by flash) and background (out of flash range).

Other modes

• Although also sometimes used as a scenery mode, macro modes are often not used with the scene mode and rather only change the focus area and nothing else.

• Some cameras provide options of fine-tuning things such as sharpness and saturation, which may be referred to as “Styles” or “Films”.

• Some cameras offer color-altering settings to do things such as make the photograph black-and-white, sepia tone, swap specific colors, or isolate colors.

9.7.4 See also

• Mode dial

• Digital camera

• Photography

• DSLR

• List of digital single-lens reflex cameras

9.7.5 References

[1] Miles Green. “Scenarios with TAv, Av, Tv and Manual mode in changing light”. Retrieved January 28, 2014.

[2] Jim Keenan. “Pentax K-50 Review”. Retrieved January 28, 2014.

[3] DEP – Canon’s Little-Understood Depth-of-Field Exposure Mode and How to Use it Effectively, Luminous Landscape

[4] Nikon D3 and D300: Nikon’s Latest DSLRs, and a Biased Evaluation of The Differences Between the Nikon and Canon Brands, The Luminous Landscape, January 2008

[5] ISO Control from Nikon

[6] Release Priority vs. Focus Priority 176 CHAPTER 9. DAY 9

A mode dial showing shutter priority mode.

9.8 Shutter priority

Shutter priority refers to a setting on some cameras that allows the user to choose a specific shutter speed while the camera adjusts the aperture to ensure correct exposure. This is different from manual mode, where the user must decide both values, aperture priority where the user picks an aperture with the camera selecting the shutter speed to match, or program mode where the camera selects both. Shutter priority with longer exposures is chosen to create an impression of motion. For example, a waterfall will appear blurred and fuzzy. If the camera is panned with a moving subject, the background will appear blurred. When photographing sports or high-speed phenomena, shutter priority with short exposures can ensure that the motion is effectively frozen in the resulting image. Like aperture priority, this mode allows for partial automation thus decreasing the need for total concentration. Shutter priority is often abbreviated as S (with Nikon, Minolta, Konica Minolta, Sony, Olympus, Sigma, Panasonic) or Tv (for “time value” with Canon, Pentax, Leica) on a camera mode dial.[1]

9.8.1 See also

• List of digital camera modes

• Aperture priority

9.8.2 References

[1] http://dougkerr.net/Pumpkin/articles/APEX.pdf 9.9. APERTURE PRIORITY 177

A Nikon style mode dial showing aperture priority mode.

9.9 Aperture priority

Aperture priority, often abbreviated A or Av (for aperture value) on a camera mode dial, is a setting on some cameras that allows the user to set a specific aperture value (f-number) while the camera selects a shutter speed to match it that will result in proper exposure based on the lighting conditions as measured by the camera’s light meter. This is different from manual mode, where the user must decide both values, shutter priority where the user picks a shutter speed with the camera selecting an appropriate aperture, or program mode where the camera selects both.[1]

9.9.1 Uses

Depth of field

As an image’s depth of field is inversely proportional to the size of the lens’s aperture, aperture priority mode is often used to allow the photographer to control the focus of objects in the frame. Aperture priority is therefore useful in , for example, where it may be desired that objects in foreground, middle distance, and background all be rendered crisply, while shutter speed is immaterial. To obtain this large depth of field, a narrow aperture (identified by a high f-number, e.g. f/16 or f/22) is necessary. Aperture priority mode also finds use in portrait photography, where a wide aperture (identified by a low number, e.g. f/1.4 or f/2.8) and therefore smaller depth of field may be desired to throw the background out of focus and make it less distracting.[1]

Shutter speed

Another common use of aperture priority mode is to indirectly affect shutter speed for a desired effect. In landscape photography, a user might select a small aperture when photographing a waterfall, so that the camera will select a slow shutter speed (to allow a sufficient amount of light to reach the film or sensor for proper exposure), thereby causing the water to blur through the frame.[2] When shooting a portrait in dim lighting, the photographer might choose to open the lens to its maximum aperture in hopes of getting enough light for a good exposure while maintaining the shortest possible shutter speed to reduce blur. 178 CHAPTER 9. DAY 9

9.9.2 See also

• Digital camera modes • Shutter priority

9.9.3 References

[1] Gibson, Andrew S. (12 May 2012). “Aperture Priority and Shutter Priority: Exposure Lesson #1”. Digital Photography School. Archived from the original on 18 July 2016. Retrieved 21 July 2016.

[2] Hoffmann, Reed. “How to Shoot Blurry Water Photos”. reedhoffmann.com. Archived from the original on 15 October 2013. Retrieved 22 July 2016.

9.10 Sensitivity priority

Main article: List of digital camera modes

Sensitivity priority, often abbreviated Sv (for Sensitivity value) on a camera dial, and colloquially called “ISO pri- ority”, is a setting on Pentax cameras that allows the user to choose a specific Sensitivity (ISO speed) value while the camera selects a shutter speed and aperture to match. The camera will ensure proper exposure. This is different from manual mode, where the user must decide all three values, shutter priority where the user picks a shutter speed with the camera selecting the aperture to match, or program mode where the camera selects all three. On other cameras, such as those from Canon and Nikon, this is not a distinguished mode. Rather, ISO can be set manually in all modes, or (sometimes) set to auto, and thus sensitivity priority is equivalent to manual ISO and program mode, in both cases automatically selecting aperture and shutter speed, with a manual ISO setting.

9.10.1 See also

Reasons for using:

• Exposure (photography)

• Depth of field

Other 'modes:'

• Shutter priority

• Aperture priority • Mode dial Chapter 10

Day 10

10.1 Bayer filter

Not to be confused with Bayes filter. “RGBG” redirects here. For the subpixel matrix scheme used in electronic device displays, see PenTile RGBG. A Bayer filter mosaic is a color filter array (CFA) for arranging RGB color filters on a square grid of photosensors.

The Bayer arrangement of color filters on the pixel array of an image sensor

Its particular arrangement of color filters is used in most single-chip digital image sensors used in digital cameras, camcorders, and scanners to create a color image. The filter pattern is 50% green, 25% red and 25% blue, hence is also called RGBG,[1][2] GRGB,[3] or RGGB.[4] It is named after its inventor, Bryce Bayer of Eastman Kodak. Bayer is also known for his recursively defined matrix used in ordered dithering. Alternatives to the Bayer filter include both various modifications of colors and arrangement and completely different technologies, such as color co-site sampling, the Foveon X3 sensor, the dichroic mirrors or a transparent diffractive- filter array.[5]

179 180 CHAPTER 10. DAY 10

Incoming light

Filter layer

Sensor array

Resulting pattern

Profile/cross-section of sensor

10.1.1 Explanation

Bryce Bayer’s patent (U.S. Patent No. 3,971,065[6]) in 1976 called the green photosensors luminance-sensitive ele- ments and the red and blue ones chrominance-sensitive elements. He used twice as many green elements as red or blue to mimic the physiology of the human eye. The luminance perception of the human retina uses M and L cone cells combined, during daylight vision, which are most sensitive to green light. These elements are referred to as sensor elements, sensels, pixel sensors, or simply pixels; sample values sensed by them, after interpolation, become image pixels. At the time Bayer registered his patent, he also proposed to use a cyan--yellow combination, that is another set of opposite colors. This arrangement was unpractical at the time because the necessary dyes did not exist, but is used in some new digital cameras. The big advantage of the new CMY dyes is that they have an improved light absorption characteristic; that is, their quantum efficiency is higher. The raw output of Bayer-filter cameras is referred to as a Bayer pattern image. Since each pixel is filtered to record only one of three colors, the data from each pixel cannot fully specify each of the red, green, and blue values on its own. To obtain a full-color image, various demosaicing algorithms can be used to interpolate a set of complete red, green, and blue values for each pixel. These algorithms make use of the surrounding pixels of the corresponding colors to estimate the values for a particular pixel. Different algorithms requiring various amounts of computing power result in varying-quality final images. This can be done in-camera, producing a JPEG or TIFF image, or outside the camera using the raw data directly from the sensor.

10.1.2 Demosaicing

Demosaicing can be performed in different ways. Simple methods interpolate the color value of the pixels of the same color in the neighborhood. For example once the chip has been exposed to an image, each pixel can be read. A pixel with a green filter provides an exact measurement of the green component. The red and blue components for this pixel are obtained from the neighbors. For a green pixel, two red neighbors can be interpolated to yield the red value, also two blue pixels can be interpolated to yield the blue value. This simple approach works well in areas with constant color or smooth gradients, but it can cause artifacts such as color bleeding in areas where there are abrupt changes in color or brightness especially noticeable along sharp edges in the image. Because of this, other demosaicing methods attempt to identify high-contrast edges and only interpolate 10.1. BAYER FILTER 181 along these edges, but not across them. Other algorithms are based on the assumption that the color of an area in the image is relatively constant even under changing light conditions, so that the color channels are highly correlated with each other. Therefore, the green channel is interpolated at first then the red and afterwards the blue channel, so that the color ratio red-green respective blue- green are constant. There are other methods that make different assumptions about the image content and starting from this attempt to calculate the missing color values.

10.1.3 Artifacts

Images with small-scale detail close to the resolution limit of the digital sensor can be a problem to the demosaicing algorithm, producing a result which is not looking like the model. The most frequent artifact is Moiré, which may appear as repeating patterns, color artifacts or pixels arranged in an unrealistic maze-like pattern

False color artifact

A common and unfortunate artifact of Color Filter Array (CFA) demosaicing is what is known and seen as false coloring. Typically this artifact manifests itself along edges, where abrupt or unnatural shifts in color occur as a result of misinterpolating across, rather than along, an edge. For preventing and removing this false coloring various methods exist. Smooth hue transition interpolation is used during the demosaicing to prevent false colors from manifesting themselves in the final image. However, there are other algorithms that can remove false colors after demosaicing. These have the benefit of removing false coloring artifacts from the image while using a more robust demosaicing algorithm for interpolating the red and blue color planes.

Zippering artifact

The zippering artifact is another side effect of CFA demosaicing, which also occurs primarily along edges, is known as the zipper effect. Simply put, zippering is another name for edge blurring that occurs in an on/off pattern along an edge. This effect occurs when the demosaicing algorithm averages pixel values over an edge, especially in the red and blue planes, resulting in its characteristic blur. As mentioned before, the best methods for preventing this effect are the various algorithms which interpolate along, rather than across image edges. Pattern recognition interpolation, adaptive color plane interpolation, and directionally weighted interpolation all attempt to prevent zippering by interpolating along edges detected in the image. However, even with a theoretically perfect sensor that could capture and distinguish all colors at each photosite, Moiré and other artifacts could still appear. This is an unavoidable consequence of any system that samples an otherwise continuous signal at discrete intervals or locations. For this reason, most photographic digital sensor incorporates something called an optical low-pass filter (OLPF) or an anti-aliasing (AA) filter. This is typically a thin layer directly in front of the sensor, and works by effectively blurring any potentially problematic details that are finer than the resolution of the sensor.

10.1.4 Modifications

Main article: Color filter array The Bayer filter is almost universal on consumer digital cameras. Alternatives include the CYGM filter (cyan, yellow, green, magenta) and RGBE filter (red, green, blue, emerald), which require similar demosaicing. The Foveon X3 sensor (which layers red, green, and blue sensors vertically rather than using a mosaic) and arrangements of three separate CCDs (one for each color) don't need demosaicing.

“Panchromatic” cells

On June 14, 2007, Eastman Kodak announced an alternative to the Bayer filter: a color-filter pattern that increases the sensitivity to light of the image sensor in a digital camera by using some “panchromatic” cells that are sensitive to all wavelengths of visible light and collect a larger amount of light striking the sensor.[7] They present several patterns, but none with a repeating unit as small as the Bayer pattern’s 2×2 unit. 182 CHAPTER 10. DAY 10

Another 2007 U.S. patent filing, by Edward T. Chang, claims a sensor where “the color filter has a pattern comprising 2×2 blocks of pixels composed of one red, one blue, one green and one transparent pixel,” in a configuration intended to include infrared sensitivity for higher overall sensitivity.[8] The Kodak patent filing was earlier.[9] Such cells have previously been used in "CMYW" (cyan, magenta, yellow, and white)[10] “RGBW” (red, green, blue, white)[11] sensors, but Kodak has not compared the new filter pattern to them yet.

Fujifilm “EXR” color filter array

Fujifilm’s EXR color filter array are manufactured in both CCD (SuperCCD) and CMOS (BSI CMOS). As with the SuperCCD, the filter itself is rotated 45 degrees. Unlike conventional Bayer filter designs, there are always two adjacent photosites detecting the same color. The main reason for this type of array is to contribute to pixel “binning”, where two adjacent photosites can be merged, making the sensor itself more “sensitive” to light. Another reason is for the sensor to record two different exposures, which is then merged to produce an image with greater dynamic range. The underlying circuitry has two read-out channels that take their information from alternate rows of the sensor. The result is that it can act like two interleaved sensors, with different exposure times for each half of the photosites. Half of the photosites can be intentionally underexposed so that they fully capture the brighter areas of the scene. This retained highlight information can then be blended in with the output from the other half of the sensor that is recording a 'full' exposure, again making use of the close spacing of similarly colored photosites.

Fujifilm “X-Trans” filter

The Fujifilm X-Trans CMOS sensor used in many Fujifilm X-series cameras is claimed[12] to provide better resistance to color moiré than the Bayer filter, and as such they can be made without an anti-aliasing filter. This in turn allows cameras using the sensor to achieve a higher resolution with the same megapixel count. Also, the new design is claimed to reduce the incidence of false colors, by having red, blue and green pixels in each line. The arrangement of these pixels is also said to provide grain more like film. One of main drawbacks is that support for custom pattern can lack full support in third party RAW processing software like Adobe Photoshop Lightroom[13] where adding improvements took multiple years.[14]

10.1.5 See also

• Autochrome Lumière

• PenTile matrix family

10.1.6 References

• US patent 3971065, Bryce E. Bayer, “Color imaging array”, issued 1976-07-20 on web

10.1.7 Notes

[1] Jeff Mather (2008). “Adding L* to RGBG”.

[2] dpreview.com (2000). “Sony announce 3 new digital cameras”. Archived from the original on 2011-07-21.

[3] Margaret Brown (2004). Advanced Digital Photography. Media Publishing. ISBN 0-9581888-5-8.

[4] Thomas Maschke (2004). Digitale Kameratechnik: Technik digitaler Kameras in Theorie und Praxis. Springer. ISBN 3-540-40243-8.

[5] Wang, Peng; Menon, Rajesh (29 October 2015). “Ultra-high-sensitivity color imaging via a transparent diffractive-filter array and computational optics”. Optica. 2 (11): 933. doi:10.1364/optica.2.000933.

[6] Patent US3971065 - Color imaging array - Google Patents

[7] John Compton and John Hamilton (2007-06-14). “Color Filter Array 2.0”. A Thousand Nerds: A Kodak blog. Archived from the original on 2007-07-20. Retrieved 2011-02-25. 10.1. BAYER FILTER 183

[8] “US patent publication 20070145273 “High-sensitivity infrared color camera"".

[9] “US Patent Application 20070024879 “Processing color and panchromatic pixels"".

[10] L. J. d'Luna; et al. (1989). “A digital video signal post-processor for color image sensors”. Proceedings of the Custom Integrated Circuits Conference. 1989: 24.2/1. doi:10.1109/CICC.1989.56823. A variety of CFA patterns can be used, with various arrangements of red, green, and blue (RGB) or of cyan, magenta, yellow, and white (CMYW) colors.

[11] Sugiyama, Toshinobu, US patent application 20050231618, “Image-capturing apparatus”, filed March 30, 2005

[12] “Fujifilm X-Trans sensor technology”. Archived from the original on 2012-04-09. Retrieved 2012-03-15.

[13] Diallo, Amadou. “Adobe’s Fujifilm X-Trans sensor processing tested”. dpreview.com. Retrieved 20 October 2016.

[14] “Adobe Improves X-Trans Processing in Lightroom CC Update: Promises More to Come”. Thomas Fitzgerald Photogra- phy Blog. Retrieved 20 October 2016.

10.1.8 External links

• RGB “Bayer” Color and MicroLenses, Silicon Imaging (design, manufacturing and marketing of high-definition digital cameras and image processing solutions)

• eLynx image processing library, Big set of Bayer mosaic manipulation source code under GPL. • Efficient, high-quality Bayer demosaic filtering on GPUs

• http://www.inf.fu-berlin.de/lehre/WS02/robotik/Vorlesungen/Vorlesung2/ComputerVision-2.pdf • http://www.arl.army.mil/arlreports/2010/ARL-TR-5061.pdf

• http://www.cambridgeincolour.com/tutorials/camera-sensors.htm 184 CHAPTER 10. DAY 10

1. Original scene 2. Output of a 120-pixel × 80-pixel sensor with a Bayer filter 3. Output color-coded with Bayer filter colors 4. Reconstructed image after interpolating missing color information 10.1. BAYER FILTER 185

Three images depicting the false color demosaicing artifact.

Three images depicting the zippering artifact of CFA demosaicing

Three new Kodak RGBW filter patterns 186 CHAPTER 10. DAY 10

Earlier RGBW filter pattern 10.1. BAYER FILTER 187

EXR sensor 188 CHAPTER 10. DAY 10

The repeating 6×6 grid used in the x-trans sensor 10.1. BAYER FILTER 189

Front page of Bryce Bayer’s 1976 patent on the Bayer pattern filter mosaic, showing his terminology of luminance-sensitive and chrominance-sensitive elements 190 CHAPTER 10. DAY 10

10.2 Color filter array

The Bayer color filter mosaic. Each two-by-two submosaic contains 2 green, 1 blue and 1 red filter, each covering one pixel sensor.

In photography, a color filter array (CFA), or color filter mosaic (CFM), is a mosaic of tiny color filters placed over the pixel sensors of an image sensor to capture color information. Color filters are needed because the typical photosensors detect light intensity with little or no wavelength specificity, and therefore cannot separate color information.[1] Since sensors are made of they obey solid-state physics. The color filters filter the light by wavelength range, such that the separate filtered intensities include information about the color of light. For example, the Bayer filter (shown to the right) gives information about the intensity of light in red, green, and blue (RGB) wavelength regions. The raw image data captured by the image sensor is then converted to a full-color image (with intensities of all three primary colors represented at each pixel) by a demosaicing algorithm which is tailored for each type of color filter. The spectral transmittance of the CFA elements along with the demosaicing algorithm jointly determine the color rendition.[2] The sensor’s passband quantum efficiency and span of the CFA’s spectral responses are typically wider than the visible spectrum, thus all visible colors can be distinguished. The responses of the filters do not generally correspond to the CIE color matching functions,[3] so a color translation is required to convert the tristimulus values into a common, absolute .[4] The Foveon X3 sensor uses a different structure such that a pixel utilizes properties of multi-junctions to stack blue, green, and red sensors on top of each other. This arrangement does not require a demosaicing algorithm because each pixel has information about each color. Dick Merrill of Foveon distinguishes the approaches as “vertical color filter” for the Foveon X3 versus “lateral color filter” for the CFA.[5][6]

10.2.1 List of color filter arrays

10.2.2 RGBW sensor

An RGBW matrix (from Red, Green, Blue, White) is a CFA that includes “white” or transparent filter elements that allow the photodiode to respond to all colors of light; that is, some cells are “panchromatic”, and more of the light is detected, rather than absorbed, compared to the Bayer matrix. Sugiyama filed for a patent on such an arrangement in 2005.[7] Kodak announced several RGBW CFA patents in 2007, all of which have the property that when the 10.2. COLOR FILTER ARRAY 191 panchromatic cells are ignored, the remaining color filtered cells are arranged such that their data can be processed with a standard Bayer demosaicing algorithm.

10.2.3 CYGM sensor

A CYGM matrix (Cyan, Yellow, Green, Magenta) is a CFA that uses mostly secondary colors, again to allow more of the incident light to be detected rather than absorbed. Other variants include CMY and CMYW matrices.

10.2.4 Manufacture of the CFA

Diazonaphthoquinone (DNQ)-novolac photoresist is one material used as the carrier for making color filters from color dyes. There is some interference between the dyes and the ultraviolet light needed to properly expose the polymer, though solutions have been found for this problem.[8] Color photoresists sometimes used include those with chemical monikers CMCR101R, CMCR101G, CMCR101B, CMCR106R, CMCR106G, and CMCR106B.[9] A few sources[1][10] discuss other specific chemical substances, attending optical properties, and optimal manufactur- ing processes of color filter arrays. For instance, Nakamura said that materials for on-chip color filter arrays fall into two categories: pigment and dye. Pigment based CFAs have become the dominant option because they offer higher heat resistance and light resistance compared to dye based CFAs. In either case, thicknesses ranging up to 1 micrometre are readily available.[1] Theuwissen says “Previously, the color filter was fabricated on a separate glass plate and glued to the CCD (Ishikawa 1981), but nowadays, all single-chip color cameras are provided with an imager which has a color filter on-chip processed (Dillon, 1978) and not as a hybrid.”[10] He provides a bibliography focusing on the number, types, aliasing effects, moire patterns, and spatial frequencies of the absorptive filters. Some sources indicate that the CFA can be manufactured separately and affixed after the sensor has been manufactured,[11][12][13] while other sensors have the CFA manufactured directly on the surface of the imager.[13][14][15] Theuwissen makes no mention of the materials utilized in CFA manufacture. At least one early example of an on-chip design utilized filters (Aoki et al., 1982).[16] The gelatin is section- alized, via photolithography, and subsequently dyed. Aoki reveals that a CYWG arrangement was used, with the G filter being an overlap of the Y and C filters. Filter materials are manufacturer specific.[17] Adams et al. state “Several factors influence the CFA’s design. First, the individual CFA filters are usually layers of transmissive (absorptive) organic or pigment dyes. Ensuring that the dyes have the right mechanical properties—such as ease of application, durability, and resistance to humidity and other atmospheric stresses—is a challenging task. This makes it difficult, at best, to fine-tune the spectral responsivities.”. Given that the CFAs are deposited on the image sensor surface at the BEOL (back end of line, the later stages of the integrated circuit manufacturing line), where a low-temperature regime must be rigidly observed (due to the low melting temperature of the aluminum metalized “wires” and the substrate mobility of the dopants implanted within the bulk silicon), organics would be preferred over glass. On the other hand, some CVD silicon oxide processes are low temperature processes.[18] Ocean Optics has indicated that their patented dichroic filter CFA process (alternating thin films of ZnS and Cryolite) can be applied to spectroscopic CCDs.[19] Gersteltec sells photoresists that possesses color filter properties.[20]

Some pigment and dye molecules used in CFAs

In U.S.P.# 4,808,501, Carl Chiulli cites the use of 5 chemicals, three of which are C.I. #12715, AKA Solvent Red 8; Solvent Yellow 88; and C.I. # 61551, Solvent Blue 36. In U.S.P. # 5,096,801 Koya et al., of Fuji Photo Film company, list some 150-200 chemical structures, mainly azo dyes and pyrazolone-diazenyl, but fail to provide chemical names, CAS Registry numbers, or Colour Index numbers.

Optically efficient CFA implementation

Nakamura[1] provides a schematic and bibliographic items illustrating the importance of microlenses, their f-number, and the interplay with the CFA and CCD array.[21] Further, a short discussion of anti-reflection films is offered,[22] 192 CHAPTER 10. DAY 10 though Janesick’s[23] work appears is more concerned with photon–silicon interaction. Early work on microlenses[24] and on the three-CCD/prism cameras[25] stress the importance of a fully integrated design solution for CFAs. The camera system, as a whole, benefits from careful consideration of CFA technologies and their interplay with other sensor properties.

10.2.5 References

[1] Nakamura, Junichi (2005). Image Sensors and Signal Processing for Digital Still Cameras. CRC Press. ISBN 978-0-8493- 3545-7. [2] “Color Correction for Image Sensors” (PDF). Image Sensor Solutions: Application Note. Revision 2.0. Kodak. 27 October 2003. [3] Comparison of the spectral response of a vs. Canon 10D, Christian Buil. [4] Soo-Wook Jang; Eun-Su Kim; Sung-Hak Lee; Kyu-Ik Sohng (2005). Adaptive Colorimetric Characterization of Digital Camera with White Balance. LNCS. 3656. Springer. pp. 712–719. doi:10.1007/11559573_87. ISBN 978-3-540-29069- 8. ISSN 1611-3349. [5] “Digital Photography Essentials #003: “Color Separation"". Digital Outback Photo. [6] Thomas Kreis (2006). Handbook of Holographic Interferometry: Optical and Digital Methods. Wiley-VCH. ISBN 3-527- 60492-8. [7] US Patent Application 20050231618 [8] Miller Harris R. (1999). “Color filter array for CCD and CMOS image sensors using a chemically amplified, thermally cured, pre-dyed, positive-tone photoresist for 365 nm lithography”. Proceedings of SPIE. International Society for Optical Engineering. 3678 (2): 1083–1090. doi:10.1117/12.350159. ISSN 0277-786X. [9] “Microelectronics Fabrication Facility, Hong Kong University of Science and Technology”. [10] Theuwissen, Albert (1995). Solid-State Imaging with charge coupled devices. Kluwer Academic Publishers. ISBN 978-0- 7923-3456-9. [11] Ishikawa; et al. (1981). Color Reproduction of a Single Chip Color Camera with a Frame Transfer CCD. IEEE Journal of Solid-State Circuits, Vol. SC-16, No. 2, April 1981. [12] Takizawa; et al. (1983). Field Integration Mode CCD Color Television Camera Using Frequency Interleaving Method. IEEE Transactions on , Vol. CE-29, No. 3, August 1983. [13] Knop and Morf (1985). A New Class of Mosaic Color Encoding Patterns for Single-Chip Cameras. IEEE Transactions on Electron Devices, Vol. ED-32, No. 8, August 1985. [14] Dillon; et al. (1978). IEEE. Missing or empty |title= (help) [15] Tanaka; et al. (1990). HDTV Single-Chip CCD Color Camera. IEEE Transactions on Consumer Electronics, Vol. CE-36, No. 3, August 1990. [16] Aoki; et al. (1982). 2/3-Inch Format MOS Single-Chip Color Imager. IEEE Transactions on Electron Devices, Vol. ED-29, No. 4, April 1982. [17] Adams; et al. (1998). Color Processing in Digital Cameras. IEEE Micro. 1998, Vol. 18, Issue 6. Pgs. 20-31. [18] Xiao (2001). Introduction to Semiconductor Manufacturing. [19] “Dichroic Filter Array Patented Patterned Technology”. Ocean Optics. [20] “Swiss made SU-8 Photoepoxy Functional Products”. Gersteltec Engineering Solutions. [21] Agranov; et al. (January 2003). “Crosstalk and Microlens Study in a Color CMOS Image Sensor”. IEEE Transactions on Electron Devices. 50 (1): 4–11. doi:10.1109/ted.2002.806473. ISSN 0018-9383. [22] Murakami; et al. (2000). Technologies to Improve Photo-Sensitivity and Reduce VOD Shutter Voltage for CCD Image Sensors. IEEE Transactions on Electron Devices, Vol. 47, No. 8, August 2000. ISSN 0018-9383. [23] Janesick, James (2001). Scientific Charge Coupled Devices. SPIE. ISBN 0-8194-3698-4. [24] Ishihara and Tanigaki (1983). A High Photosensitivity IL-CCD Image Sensor with Monolithic Resin Lens Array. IEEE International Electron Devices Meeting (IEDM) Technical Digest. doi:10.1109/IEDM.1983.190552. [25] Murata; et al. (1983). Development of a 3-MOS Color Camera. SMPTE Journal, December, 1983. 10.2. COLOR FILTER ARRAY 193

10.2.6 See also

• Bayer filter • CYGM filter

• RGBE filter • Foveon X3 sensor

• Three-CCD camera Chapter 11

Text and image sources, contributors, and licenses

11.1 Text

• Camera Source: https://en.wikipedia.org/wiki/Camera?oldid=763658670 Contributors: Brion VIBBER, Mav, Robert Merkel, The Anome, Malcolm Farmer, Andre Engels, SimonP, Merphant, Ellmist, Topory, Ericd, Stevertigo, Frecklefoot, Patrick, Gabbe, Egil, Ams80, Aho- erstemeier, Jebba, Rl, Mxn, Smack, TheStick, Agtx, SEWilco, Bevo, Shizhao, Michael Glass, Shantavira, Nufy8, Robbot, Pigsonthew- ing, Romanm, Academic Challenger, Bertie, Rrjanbiah, Hadal, Seano1, HaeB, Cyrius, Dina, Alan Liefting, ShutterBugTrekker, Ævar Arnfjörð Bjarmason, Kurt Eichenberger, Ruckus~enwiki, Dissident, Peruvianllama, Everyking, Jason Quinn, Jackol, Supaluminal, Lu- casVB, Dscos, Antandrus, MarkSweep, Satori, Zfr, Monk Bretton, Lindberg G Williams Jr, P G Henning, Ukexpat, Fg2, Robin klein, Canterbury Tail, Mike Rosoft, Jayjg, Imroy, Discospinster, Rama, Gku, ESkog, Sum0, Pedant, CanisRufus, Doron, Nosoccomtothom, Bobo192, Kghose, Jeffmedkeff, Smalljim, John Vandenberg, Thebassman, Andrewfields, ParticleMan, Sam Korn, Hooperbloob, Nsaa, Danski14, Alansohn, Polarscribe, Atlant, Andrew Gray, Nasukaren, Ynhockey, Redfarmer, Fourthgeek, CJ, Hu, Snowolf, Wtmitchell, Velella, Dtcdthingy, Max Naylor, Versageek, Redvers, Recury, HenryLi, Isfisk, Kelly Martin, The JPS, OwenX, Woohookitty, RHaworth, Rocastelo, Thorpe, Bkkbrad, Carcharoth, Nvinen, Mandards, Pol098, WadeSimMiser, Gxojo, Mrs Trellis, Tabletop, Schzmo, CharlesC, Kralizec!, Toussaint, Dysepsion, David Levy, FreplySpang, SpaceToast, Dvyost, Ketiltrout, Sjö, Kember, Panoptical, Pleiotrop3, Cam- bridgeincolour, Patrick Gill, Tangotango, Sdornan, Mentality, Mitrebox, Miha Ulanov, ElKevbo, The wub, Ohanian, Nandesuka, Sango123, Yamamoto Ichiro, Franzeska, Darkest90, Resistwiki, Windchaser, Old Moonraker, Andrewchang, Nihiltres, RexNL, Gurch, Srleffler, Utopos, King of Hearts, Chobot, DVdm, UkPaolo, Wavelength, Luke Bales, Sceptre, Phantomsteve, Conscious, SpuriousQ, Stephenb, Manop, Mithridates, Gaius Cornelius, Zhatt, Rsrikanth05, Wimt, RadioKirk, Wikimachine, David R. 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194 11.1. TEXT 195

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• Camera obscura Source: https://en.wikipedia.org/wiki/Camera_obscura?oldid=762909283 Contributors: Brion VIBBER, Mav, Bryan Derksen, Zundark, Tarquin, Malcolm Farmer, Andre Engels, Ortolan88, Shii, Heron, Tedernst, Topory, Ericd, Renata, Stevertigo, Michael Hardy, Liftarn, Ixfd64, Ahoerstemeier, Stan Shebs, William M. Connolley, Snoyes, IMSoP, Norwikian, Charles Matthews, Furrykef, Chuunen Baka, Robbot, Kent Wang, Kevo00, Seth Ilys, Alan Liefting, Craig Butz, Ancheta Wis, Kurt Eichenberger, Fleminra, Rookkey, Dmmaus, Willhsmit, Ukexpat, Janneok~enwiki, ELApro, Thorwald, Auricfuzz, Mike Rosoft, Imroy, Discospinster, LindsayH, Alis- tair1978, Bender235, Verbalcontract, Violetriga, Art LaPella, Bookofjude, Meggar, LuoShengli, MPerel, Polylerus, Alansohn, Geke, Rodw, Eagleridge, Hoary, JPDW, Cburnett, Kusma, Zosodada, Bobrayner, Nuno Tavares, Mindmatrix, Merlinme, Rocastelo, Misterjta, Mandarax, DavidParfitt, Graham87, Sparkit, Vanderdecken, TheRingess, Mencial, DirkvdM, Downtownee, Latka, President Rhapsody, SteveBaker, Srleffler, Gdrbot, Bgwhite, Gnidan, Spacepotato, RussBot, Ioerror, Conscious, Epolk, Shell Kinney, Pseudomonas, Neil- beach, NawlinWiki, Brandon, Brian Crawford, Jpbowen, RL0919, Dbfirs, FiggyBee, Alpha 4615, Mike Dillon, 2fort5r, Dontaskme, Curpsbot-unicodify, GrinBot~enwiki, Nekura, DVD R W, KnightRider~enwiki, SmackBot, Iamhove, InverseHypercube, NoelWalley, Jagged 85, Eskimbot, Jim Casper, Peter Isotalo, Hmains, Durova, Darrellk, Boomshanka, Scwlong, Nixeagle, OOODDD, Xmastree, Rrburke, Benjaminpender, Arab Hafez, Iain4724, Underbar dk, Clicketyclack, SashatoBot, Eliyak, Valfontis, SilkTork, Gobonobo, Breno, Tony Corsini, Tktktk, Minna Sora no Shita, Cbaer, IronGargoyle, Sohale, Dicklyon, Hu12, Iridescent, Sam Clark, Igoldste, BooDog, Ellin Beltz, R N Talley, BeenAroundAWhile, Thuen, Ibadibam, Fork me, Daksol, Rouis.k, AndrewCStuart, Jds10, Futonrevo- lutionary, Tawkerbot4, Paddles, JohnClarknew, Rosser1954, Thijs!bot, Epbr123, Wikid77, Edal, Ferrarama, AntiVandalBot, Punctured Bicycle, Modernist, Hushus20, Paul1776, Barek, Albany NY, Agreene175, PhilKnight, Shaul1, Freshacconci, VoABot II, JamesBWat- son, Stigmj, Nyttend, Froid, Avicennasis, Fabrictramp, Dave Muscato, Juansidious, Keith D, Mostly water, Killer4571, Jimmybob123, Rizan, BrokenSphere, Johnbod, Koven.rm, Paleo-camera, Is anything not in use, Chiswick Chap, Kansas Bear, Flamesplash, Scewing, Idioma-bot, Funandtrvl, Valugi, Deor, Thedjatclubrock, Erdesky, Indubitably, Amikake3, Barneca, Philip Trueman, DoorsAjar, Flam- inghomeryto, Dra3b, Obscuriosity, Sina7, Broadbot, LeaveSleaves, Schiec, Aamackie, Wolfrock, Falcon8765, PericlesofAthens, SieBot, Tiddly Tom, WereSpielChequers, Laoris, Totally screwed, NigelLumsden, Oxymoron83, Baseball Bugs, Spitfire19, LonelyMarble, Per- ryTachett, Tomasz Prochownik, ClueBot, GorillaWarfare, Wikievil666, The Thing That Should Not Be, Wxyz098, Mild Bill Hiccup, J8079s, Robby.is.on, Boing! said Zebedee, Brain seltzer, Miyagaya, Lensicon~enwiki, Piledhigheranddeeper, Alexbot, RPSM, Yemal, NuclearWarfare, Obscurantist, ChrisHodgesUK, Unrealwriter, The Yowser, Mhockey, DumZiBoT, Stickee, Avoided, Lacomba, Broehm, Airplaneman, Doug butler, Addbot, Julzzz~enwiki, CanadianLinuxUser, MrOllie, Download, FiriBot, Chzz, SpBot, Peti610botH, Light- bot, Zorrobot, Luckas-bot, Yobot, Fraggle81, Auronrenouille, AnomieBOT, Rubinbot, Jim1138, Piano non troppo, Michaelkirschner, Ulric1313, Bluerasberry, Materialscientist, E2eamon, ArthurBot, MauritsBot, Xqbot, Dronne, Poetaris, Mononomic, Armbrust, Om- nipaedista, SassoBot, Erik9, Maria1853, FrescoBot, Tobby72, Citation bot 1, Pinethicket, MJ94, RedBot, Lars Washington, Fumitol, 196 CHAPTER 11. TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

Code6840, Hexrei2, FoxBot, TBloemink, Ripchip Bot, DASHBot, EmausBot, WikitanvirBot, Joshua6107, Look2See1, Rrjr0306, Dee Fraser, K6ka, Hhhippo, ZéroBot, Bollyjeff, Knight1993, Akerans, H3llBot, Natvh4, Wayne Slam, Coasterlover1994, Shibes, AVar- chaeologist, Donner60, Saraplacid, Eklotzko, Terraflorin, GrayFullbuster, ClueBot NG, Astrocog, Rtucker913, Smokeyfire, Ekely, Widr, Williaz13, Helpful Pixie Bot, BG19bot, Communication ccl, Bstbll, Darafsh, Mmarkon, Player017, Krisrich, Visulate, CitationCleaner- Bot, Rococo1700, Glacialfox, MariaCA, BattyBot, Fluffystar, The Bearded Man, ChrisGualtieri, YFdyh-bot, Harpsichord246, JYBot, Tow, Dexbot, Jeffrey Odell, Lugia2453, Frosty, Vanamonde93, 7efty, The Herald, Jakeforbes, Redknight055, Roverlager, Kasimirsw, Ryubyss, LoDomen, Crystallizedcarbon, Lolpoopyface, Serten II, ViaticDustI, Integic, Vesuvius Dogg, Sweepy, Arnfinnrokne, Astron- omy Explained, Sitting on a Throne of Lies, Joortje1 and Anonymous: 376 • Pinhole camera Source: https://en.wikipedia.org/wiki/Pinhole_camera?oldid=763322889 Contributors: Brion VIBBER, Zundark, William Avery, DrBob, Olivier, Ericd, PhilipMW, David Martland, Egil, Glenn, Wik, RedWolf, Merovingian, Wile E. Heresiarch, Sho Uemura, Tea2min, Alan Liefting, BenFrantzDale, Art Carlson, Kurt Eichenberger, Ds13, Bobblewik, SonicAD, Christopherlin, Gadfium, Geni, MarkSweep, Kesac, Mysidia, Sam Hocevar, Alsaker, Three, Trevor MacInnis, Kate, Freakofnurture, Imroy, Discospinster, Rich Farm- brough, Duchamp~enwiki, Dave souza, Horkana, Kwamikagami, Shanes, Art LaPella, Triona, Bobo192, Sam Korn, Hooperbloob, Dan- ski14, Snowolf, Velella, RainbowOfLight, Tweek, Danner578, Bobrayner, Philthecow, OwenX, Mindmatrix, LOL, Carcharoth, WadeS- imMiser, Mandarax, Deltabeignet, Rjwilmsi, ElKevbo, Sanbeg, RexNL, Alphachimp, Srleffler, Imnotminkus, Chobot, DVdm, Bgwhite, Roboto de Ajvol, Spacepotato, H005, Kazikameuk, Van der Hoorn, Stephenb, Wimt, NawlinWiki, MrBenn, Apokryltaros, Larry , Pawyilee, Theda, CharlesHBennett, BorgQueen, Tyrenius, Fourohfour, Buybooks Marius, SkerHawx, Cmglee, Sardanaphalus, Smack- Bot, Mstahl, Dav2008, Jagged 85, Arniep, KYN, Gilliam, Anachronist, Pieter Kuiper, Nicolai g, Zetlinfiend, Schwallex, Can't sleep, clown will eat me, Mpetrizzo, EvelinaB, Lunarman, Bansp, SpellChecker, Jadedoto, Heimstern, Minna Sora no Shita, Cbaer, Eivind F Øyangen, Slakr, Frango com Nata, Booksworm, Mr Stephen, Dicklyon, Dr.K., ShakingSpirit, SimonD, B7T, Nonexistant User, Kencf0618, Joseph Solis in Australia, Xcentaur, Erik Kennedy, Sulfis, Ibadibam, Arturobandini, Mato, Dancter, Paddles, Optimist on the run, Zanhsieh, Pustelnik, JohnClarknew, Epbr123, Mactographer, Sean William, AntiVandalBot, Cjs2111, Canadian-Bacon, Davewho2, Barek, Txomin, Albany NY, AllanX, Douglas Whitaker, Freshacconci, Bongwarrior, VoABot II, Artlondon, Nyttend, JJ Harrison, DerHexer, Nbreslin, MartinBot, Rettetast, Beanmg, R'n'B, CommonsDelinker, Pbroks13, Mooglemoogle, Dojo 19, J.delanoy, EscapingLife, Cchriste, The- greenj, Rc3784, Wandering Ghost, Peppergrower, Pyrospirit, Juliancolton, Phil Gee, Deor, CompactFish, TheMindsEye, Ada shen, Barneca, Philip Trueman, Oshwah, Firestarter001, Anna Lincoln, Leafyplant, Cremepuff222, Very little gravitas indeed, Saturn star, Sven Korsgaard, Smurfoid, Petero9, Falcon8765, Ratherbeinsane, Chenzw, AlleborgoBot, PericlesofAthens, Dobs~enwiki, SieBot, Plan- etStar, Toghome, Themaskobscure, Oxymoron83, AngelOfSadness, Sunrise, Mr. Stradivarius, Davidgutschick, Martarius, ClueBot, The Thing That Should Not Be, Wow.its.alana, Sapata, Wxyz098, J8079s, RenamedUser jaskldjslak903, Khateeb88, DragonBot, Excirial, Socrates2008, Jusdafax, RPSM, Raghav96, 842U, YSH123, Kristoffersson, ChrisHodgesUK, Bjdehut, Thingg, Apparition11, XLinkBot, Rror, Sakura Cartelet, Lacomba, WikiDao, MarcM1098, Googleplex12, Addbot, Aljays, Crazysane, Mr. Wheely Guy, Cst17, MrOl- lie, Download, LaaknorBot, CarsracBot, Glane23, Gpeterw, Baffle gab1978, Mr.Xp, Lightbot, Gail, Yobot, Amble, Sg227, Elizgoiri, Eric-Wester, AnomieBOT, KDS4444, Ciphers, Redbobblehat, Materialscientist, E2eamon, Snodfrey, Capricorn42, Poetaris, Martijn Witlox, Brandon5485, Zolac1, Giftlab, AddressOk, Strice, HamburgerRadio, Pinethicket, RedBot, Serols, Shanmugamp7, Anewchar- liega, AlternativePhotography, Rostayob, Epitalon, Hambergerhead, Vrenator, Jeffrd10, Ewan McGregor, Mjdestroyerofworlds, Reach Out to the Truth, 14chongce1, Gingersnaps02689, DASHBot, Tinss, Syncategoremata, Rarevogel, Wikipelli, K6ka, Phiarc, Mcyccc, Eri- anna, Violinist67, Flightx52, Inka 888, Stroumphette, Cnetra, Petrb, ClueBot NG, Astaykov2, Habib Muradov, Braincricket, Rezabot, Widr, Rurik the Varangian, Helpful Pixie Bot, 2pem, NoodleWhacks, Darafsh, Mmarkon, AwamerT, C.uzum, PiusImpavidus, Soerfm, CitationCleanerBot, Cskirksey, Osman09, Klilidiplomus, Zolac69, ITEsafety, Guanaco55, Professorjohnas, Pscott558, Webclient101, Mogism, Numbermaniac, Isarra (HG), The Quirky Kitty, Reatlas, Epicgenius, 09swild, Theopticist, JamesMoose, Qqqee, Muua3, Pin- holequinnell, Avian appreciator, Serious Enterprises, Bjkun16, Biblioworm, 5p1d3y1699, Theindian28, Sofeshue, Leveller1980, Salty73, 123456fkrfkr, Dfvscetvtsrtvsrtv, Joortje1 and Anonymous: 480 • Single-lens reflex camera Source: https://en.wikipedia.org/wiki/Single-lens_reflex_camera?oldid=761501464 Contributors: Tobias Ho- evekamp, Magnus Manske, Derek Ross, Lee Daniel Crocker, Brion VIBBER, Robert Merkel, Koyaanis Qatsi, Ellmist, Daniel C. Boyer, Heron, Branko, Tzartzam, Ericd, Spiff~enwiki, JohnOwens, Michael Hardy, Earth, Egil, Stefan-S, Lee M, Ehn, Ed Cormany, Saltine, Morven, Robbot, Fredrik, IOOI, Rochkind, GreatWhiteNortherner, Carnildo, Alan Liefting, DocWatson42, Dawidl, Pne, Bobblewik, Edcolins, Geoffspear, Chowbok, Hananeko, Ablewisuk, Jossi, Fg2, Vitaleyes, Icd, Moxfyre, DmitryKo, MaikSchreiber, Mike Rosoft, Im- roy, Mindspillage, Discospinster, Rich Farmbrough, TomPreuss, Rama, NetguruDD, Chowells, Plugwash, Elwikipedista~enwiki, Malene, Vecrumba, Felagund, Bdoserror, Willemdd, Harald Hansen, Cmdrjameson, Johnteslade, Savvo, Jonaro~enwiki, Hooperbloob, Justinc, HasharBot~enwiki, ClementSeveillac, Polarscribe, Andrewpmk, Ashley Pomeroy, Hoary, Nasukaren, Hu, Snowolf, Wtmitchell, Cbur- nett, Tonyjose, Markdstump, Zntrip, Henrik, Mindmatrix, FvdM, Rocastelo, Splintax, Armando, Pol098, Yustas, SCEhardt, Waldir, Haunti, Pfalstad, Graham87, Nightscream, Rogerd, Crazyvas, Collard, HappyCamper, Ohanian, MikeJ9919, SchuminWeb, Slugbug, SouthernNights, Srleffler, WikiWikiPhil, Antilived, Cdmarcus, Roboto de Ajvol, Borgx, Angus Lepper, MattWright, DMahalko, Splette, Monito, Hellbus, M0RHI, Manop, Brian Crawford, Gerhard51, Raven4x4x, Misza13, Dbfirs, Shotgunlee, Falcon9x5, Samir, Kassie, Fiaschi~enwiki, Balarishi, Ziggur, Gaius julius, Petri Krohn, Toodiesel, AGToth, Raphael.bosshard, Nick R Hill, SmackBot, F, Un- yoyega, Tharsaile, Video99, Sigmund~enwiki, Chris the speller, Jerome Charles Potts, Nbarth, Colonies Chris, Mulvany, Addshore, Midnightcomm, Nakon, Mr Minchin, EVula, Derek R Bullamore, Daniel.Cardenas, Rodney Boyd, Elliotgoodrich, ML5, Paul1513, Jet Jaguar, KengRu, Dicklyon, Marimvibe, Bashari, Negrulio, Paleolith, Iridescent, Civil Engineer III, BrOnXbOmBr21, Kevin Murray, Atomobot, Slippyd, Zahn, JohnCD, Anoneditor, Rmallins, Jb17kx, Ameyjw, 663highland, Alvesgaspar, Omexis, SpK, Thijs!bot, Gr- phiw, Andyjsmith, Sobreira, Aureliano, Iulius, J Clear, Stybn, Billauer~enwiki, Seaphoto, Achra, CairoTasogare, Drake Wilson, Jessi- cabreckenridge, JAnDbot, MER-C, TAnthony, Crmtm, Jeff dean, Visu1178, Catgut, Umang.joshi, BilCat, Oicumayberight, Akashopo- holic, CommonsDelinker, Hu Totya, Thegreenj, Ahmed Elnagar, Jon Ascton, RenniePet, Carlodingo, Fountains of Bryn Mawr, SJP, Gwen Gale, Dcouzin, Idioma-bot, Funandtrvl, Lights, Multimotyl, TheMindsEye, Philip Trueman, Oshwah, Berthold Werner, A4bot, JrPol, Slysplace, Kperegoy, DesmondW, Cremepuff222, MurderWatcher1, Joglekar, Motorrad-67, SieBot, Bjfb, Baltimark, Dawn Bard, Soler97, Jimthing, Yerpo, Lightmouse, Milanfrazer, KathrynLybarger, Manway, Twinsday, ClueBot, Binksternet, Hustvedt, Aashish.59, MorganaFiolett, Buonaparte69, Boing! said Zebedee, Excirial, ParaGreen13, Egmontaz, Matthewwilletts, XLinkBot, Delicious carbun- cle, Dthomsen8, WikHead, Addbot, Some jerk on the Internet, AkhtaBot, Glane23, BrianKnez, Lightbot, KVK2005, Ralf Roletschek, Ben Ben, Luckas-bot, Yobot, Fraggle81, TheWishy, Foma39, Magog the Ogre, AnomieBOT, Ulric1313, The High Fin Sperm Whale, LilHelpa, Xqbot, Mononomic, Dellant, Niduramak, Kyng, Pereant antiburchius, SCΛRECROW, Sahehco, WikiNym, Haldraper, Fres- coBot, Dasuin, Lonaowna, Nightsturm, Gnircie09, Jehuofnimshi, Calmer Waters, Melderman, Steve2011, Mjs1991, Jan von Erpecom, DARTH SIDIOUS 2, Updatehelper, EmausBot, Ajraddatz, OCtheMIKE, CMAH, ZéroBot, H3llBot, Wagino 20100516, Thine An- tique Pen, AshleyGreen, Evan-Amos, Kadcpm88, ClueBot NG, Mahaboyd, Matthiaspaul, Cntras, Traveletti, MerlIwBot, Helpful Pixie Bot, K0 7zQY0oyqcz, Jeffrey M Dean, Frze, Duga3, Sammrud, Friendofmars, Surreytech, Cookoclock, BattyBot, Justincheng12345-bot, 11.1. TEXT 197

Mfhiller, Khazar2, Ppslr, JaconaFrere, Richard Yin, Amortias, GeorginaMat, RogerTM25, Schasta, Murrazac, HDEllipsis, Mrandyrew95 and Anonymous: 340 • Mirrorless interchangeable-lens camera Source: https://en.wikipedia.org/wiki/Mirrorless_interchangeable-lens_camera?oldid=763390671 Contributors: Samsara, Dale Arnett, Sbisolo, MaGioZal, Macrakis, Edcolins, Preroll, Slivester, Imroy, Alistair1978, Yvolution, M5, Na- sukaren, M3tainfo, Pseudopanax, BlueCanoe, Pol098, Mandarax, Seidenstud, Bubba73, Syced, Mathrick, Hydrargyrum, Janke, Welsh, Yahya Abdal-Aziz, Tony1, Shotgunlee, Petri Krohn, Bugsi, Wainstead, David Barber, SmackBot, Accurimbono, Serrin, TobyK, An- drewkantor, Chris the speller, Nbarth, Racklever, Boxersoft, Metageek, Dombi, Khazar, Roeme, Dicklyon, Iridescent, Zin92, JohnCD, Montanabw, 663highland, Gogo Dodo, Myscrnnm, Gwabell, Kozuch, Riction, Stybn, Xella, Bautsch, MER-C, The Transhumanist, Ma- gioladitis, Huseyx2, Jim.henderson, Erp Erpington, Ginsengbomb, MPJ-DK, Devonbuy, BwDraco, Darrask, Thanatos666, Aphaits, Infestor, Mourerj, Vijay.saci, JordanCS, Takeaway, Sun Creator, Warturo, Camerajohn, IamNotU, JasonAQuest, Uniquenamessuck, Addbot, Cantaloupe2, Blethering Scot, MrOllie, Pratiproy, Luckas-bot, Yobot, AnomieBOT, Ta2Ed, Cake2000, JackieBot, Eumolpo, LilHelpa, Xqbot, Polymeris, Guoguo914, FrescoBot, Lonaowna, Eyleron, Ver-bot, RedBot, Dalba, Paul Matcalfe, Lopifalko, Emaus- Bot, Dewritech, Bengt Nyman, Rmsome, Dcirovic, Ponydepression, ZéroBot, Cogiati, NJM2010, , Nickjf22, Tomy9510, Gsarwa, BadaBoom, Polisher of Cobwebs, Sin57r4, Zollo431, SkywalkerPL, Buffaboy, MarcusGR, Matthiaspaul, BarrelProof, Fauzan, Michael Barker, JSP.Zen, Kinetoa, BG19bot, ParkMel, Zagaga, SilverKylin, Soerfm, A.BourgeoisP, BattyBot, RaviSarma, Anthedog2434, Tagre- mover, Marcdaveh, HarryYTM, Mogism, Barua28, Bruxisme, Marekich, MoTorleeb, Reatlas, Charles L Davis, Melbourne Park, Comp.arch, Psygeek2, Kind Tennis Fan, InfectedMushroomOne2Three, JürgenMatern, Gilberto Pereira Junior, VeniVidiVicipedia, LUNG E.R.LG SALVATORY, Kjerish, Htchngs, PetarM, Srednuas Lenoroc, Wizardly79, Anax44, Darshank641, Joshuadalehughes, Scribolt and Anony- mous: 137 • Twin-lens reflex camera Source: https://en.wikipedia.org/wiki/Twin-lens_reflex_camera?oldid=756645703 Contributors: Topory, Er- icd, Leandrod, Michael Hardy, Liftarn, Egil, Kingturtle, Ehn, Robbot, Clngre, Jleedev, Smjg, DocWatson42, Leonard G., MikeX, Fg2, Rama, Sharkford, Sasquatch, Hooperbloob, Justinc, Fyhuang, Hoary, Btornado, Armando, Robert K S, Cbustapeck, Gisling, Bubba73, Titoxd, Chobot, YurikBot, Yrithinnd, Camerafiend, Jbattersby, Rallette, Petri Krohn, Tom Morris, RAYBAN, Ohnoitsjamie, Chris the speller, Qselby, TonyRony, MalafayaBot, Eurgain, Feelfreetoblameme, Winston Spencer, CmdrObot, Thijs!bot, Vicpino, Hpdw, Woof69, Vmuth~enwiki, DANYvanvee, Oicumayberight, Barrytoogood, CommonsDelinker, Funandtrvl, VolkovBot, Accent, Motorrad-67, Bot- Multichill, Fpmfpm, ImageRemovalBot, Mindpimp, Jin ua, DumZiBoT, Petchboo, Romanceor, Addbot, Benjamin.nagel, Lost on Bel- mont, Glane23, Lightbot, Luckas-bot, Yobot, TaBOT-zerem, Magog the Ogre, Xqbot, FrescoBot, Maxime Lardenois, MuseumGrack, Javachan, ClueBot NG, Pantergraph, Widr, K0 7zQY0oyqcz, BG19bot, Jacopo188, Glacialfox, Jimw338, Baronsen, SteenthIWbot, Lsmll, Dshlaw, Tyjstanley, GeneralizationsAreBad, Owilley and Anonymous: 52 • Image sensor Source: https://en.wikipedia.org/wiki/Image_sensor?oldid=762973769 Contributors: Glenn, Palfrey, Ehn, Boffy b, An- dries, BenFrantzDale, Mcapdevila, Ehusman, Moxfyre, Bobo192, Smalljim, Giraffedata, Trevj, The RedBurn, Ynhockey, Algocu, Pseu- dopanax, Mindmatrix, Pol098, CPES, BD2412, Rjwilmsi, Xosé, Salix alba, MZMcBride, Mahlum~enwiki, FlaBot, Enon, Srleffler, Chobot, Adoniscik, YurikBot, Groogle, Miskatonic, Shaddack, Nick, Kkmurray, MCB, Mike1024, SmackBot, Philipareed, Eflukx, In- cnis Mrsi, Slashme, Marc Lacoste, Dexter73, Pmkpmk, Oli Filth, Odoketa, Redline, LouScheffer, Midnightcomm, Aldaron, Znesic, A5b, Bjankuloski06en~enwiki, Robbins, Dicklyon, Andyhodgson, Peter Horn, Hu12, Etrevino, Papuass, Kozuch, Epbr123, MattCo- hen, Electron9, Gioto, MER-C, Hut 8.5, Papa Lima Whiskey, DANYvanvee, DerHexer, JaGa, GermanX, Jim.henderson, Reedy Bot, Oxguy3, Shervin moloudi, STBotD, D-Kuru, Funandtrvl, ICE77, NathanHagen, Anonymous Dissident, Madpogue, Luis green, Lamro, Jchen0, GavinTing, SieBot, Oxymoron83, Kuraimizu, Emesee, Blacklemon67, Dflarshe, NickCT, Meekywiki, Mild Bill Hiccup, Blud- war, Maarschalk, Alistair.s, Jytdog, Rror, Rolsby, JDSC, Addbot, Hosse~enwiki, MrOllie, Oldmountains, Quercus solaris, Tassedethe, Semiwiki, Yobot, Fraggle81, SN74LS00, DiverDave, AnomieBOT, Redbobblehat, Materialscientist, , GB fan, MauritsBot, Xqbot, JLeditor, Geekstuff, Mathonius, Madison Alex, Thenovae, Steve Farnell, Bob Flintoff, FrescoBot, Heactkin, Qwarx, Dorushiva, Alliumnsk, Verdiinpink~enwiki, Feudiable, TheRF, Swaterfall, Jmencisom, Timbobel, Salo2010, Wagino 20100516, Bjmr, Deutschgirl, Gsarwa, ClueBot NG, Natural Philo, Matthiaspaul, Bobakkh, Widr, Reify-tech, Himu.arif, PhnomPencil, Neøn, Tagremover, Davit.1980, Dexbot, VSP shines, Reatlas, Shakeshuck, Shadout mapes, M shakeri63, Minhquangdo, Golammasud, Wellset, MsGafas, Popovicsmr, Moshkitorita, Pancho507, KasparBot, Wuxijiang, RobbieIanMorrison, Acid147, Mikejyg and Anonymous: 142 • Image sensor format Source: https://en.wikipedia.org/wiki/Image_sensor_format?oldid=763306335 Contributors: Leandrod, Edward, Andrewa, BAxelrod, Dale Arnett, RedWolf, Mfc, Giftlite, BenFrantzDale, Msm, Danio, StevenBradford, Neilc, Coldacid, Moxfyre, Ell- sass, Madmaxx, Geekux, Mattdm, Alansohn, Pseudopanax, Mindmatrix, Armando, Pol098, Hotshot977, BlaiseFEgan, Arnero, Srleffler, Brandon, Hmette, Jrethorst, Anthony717, SmackBot, Norz, Stevage, Nbarth, Mwtoews, A5b, Autopilot, Khazar, Dicklyon, Peter Horn, Urebelscum, Etienne B, Joshua Lutz, Bencope, BDS2006, Lofote, Kozuch, JamesAM, Erikig, Stybn, Postlewaight, Shayno, RubyQ, JeffConrad, Jetxee, Scalvin, GermanX, Witipeter, Jim.henderson, Robijn, CFCF, Regani, Ypetrachenko, RenniePet, James Synge, San- chazo, Fountains of Bryn Mawr, Iestynne, BwDraco, CarVac, Feudonym, Francis Flinch, Ken vs ryu, Wes shaw, Motorrad-67, Flyer22 Reborn, ClassA42, YSSYguy, Sfan00 IMG, Wispanow, Stevefal, Mickydeenyc, Sun Creator, Andy16666, Addbot, G.Hagedorn, Tassede- the, Luckas-bot, Yobot, Pugglewuggle, CarsonWilson, AnomieBOT, Efa, Sorobansensei, DataWraith, JLeditor, Tobidelbruck, R69S, TorKr, FrescoBot, Dorushiva, Trappist the monk, Barry Pearson, Diannaa, Chris4877, Sirkablaam, RjwilmsiBot, MatevzB, Observer6, Dewritech, Dcirovic, Josve05a, Gsarwa, SkywalkerPL, Kristijh, Angerdan, MarcusGR, Will Beback Auto, ClueBot NG, Matthiaspaul, Jacobspeeds2, Michael Barker, Spel-Punc-Gram, Helpful Pixie Bot, Zollo9999, Fireflood, Jeffrey M Dean, Badon, Steve29418, Soerfm, St900, Anka Świteź, Bobn2, Jcmarfilph, Comfr, Tagremover, DoctorKubla, Dobie80, Mogism, SPECIFICO, Ccrescentus, Uanuanuan, Branchingfactor, Theo’s Little Bot, SelfishSeahorse, Monkbot, ReaderCritic, SomeUser1B, VincensvonBibra, EskeRahn, The Quixotic Potato, GreenC bot, Bender the Bot and Anonymous: 137 • Full-frame digital SLR Source: https://en.wikipedia.org/wiki/Full-frame_digital_SLR?oldid=761937753 Contributors: Docu, Morven, Dale Arnett, DocWatson42, Bork, Dawidl, Christopherlin, Quarl, Kaldari, Cynical, Moxfyre, Rama, Ale cyn, Ferrierd, Cburnett, Hb- dragon88, BlaiseFEgan, Ae7flux, Rogerd, Srleffler, Chobot, H005, Chensiyuan, Gaius Cornelius, Brandon, Hmette, Dspradau, Petri Krohn, Speculatrix, Sergey shandar, SmackBot, Marc Lacoste, Bluebot, ElTchanggo, Ajithpr, Morio, Autopilot, Dicklyon, Thealienfro- muranus, Tvaughan1, Zin92, Raz1el, Andrés Vattuone, Thijs!bot, LG4761, Stybn, JeffConrad, Tstrobaugh, GermanX, MBxd1, VolkovBot, Kyle the bot, Michi zh, Mudkiller, Typ932, Vitz-RS, Zombiflava, Motorrad-67, ClueBot, Wispanow, Alexbot, SpikeToronto, Sun Cre- ator, Addbot, Lightbot, Rave, Luckyz, Middayexpress, Luckas-bot, Yobot, AnomieBOT, Rockypedia, Ulric1313, Neutralis, Queiles, Jburlinson, R69S, SCΛRECROW, FrescoBot, Tttulio, Pipetricker, Serols, MightyBig, Xeworlebi, Somewhere On The Road of Life, Lopifalko, EmausBot, John of Reading, Dcirovic, ZéroBot, Protozoan321, Stonesight, SkywalkerPL, Dllu, ClueBot NG, Matthiaspaul, BroderickAU, Emagine Miker, Helpful Pixie Bot, BG19bot, Lucasbosch, BattyBot, Tagremover, EdWitt, EuroCarGT, Thewaynewu, Ajacombs, Luizmeme, Randykitty, SteveOak, Comp.arch, Saurabh Narang, Higgsbosondealer, InternetArchiveBot, Tb20, GreenC bot, Bender the Bot, Sourav1235 and Anonymous: 81 198 CHAPTER 11. TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• Digital single-lens reflex camera Source: https://en.wikipedia.org/wiki/Digital_single-lens_reflex_camera?oldid=757590597 Contrib- utors: AxelBoldt, Zadcat, Leandrod, Edward, Earth, Aimak, Ronz, Whkoh, Stefan-S, Phr, Jogloran, Buckwad, Wkcheang, Samsara, Robbot, Dale Arnett, Lowellian, David Edgar, Linulis, Alan Liefting, Javidjamae, DocWatson42, Kerttie, Inkling, Karn, Christopher- lin, Tooki, Fg2, Moxfyre, Thorwald, Imroy, Discospinster, Rich Farmbrough, Pixel8, Eric Shalov, Bender235, Darren Foong, Fir0002, Cje~enwiki, Cmdrjameson, Sasquatch, Maebmij, Pearle, Jonathunder, Jhertel, Japsu, Laug, Swaldman, Irdepesca572, Wtshymanski, Cburnett, Stephan Leeds, Lerdsuwa, Dominic, Skatebiker, Timdorr, Markaci, Forderud, AnIco, Falcorian, Thryduulf, Boothy443, Woohookitty, Mindmatrix, Pol098, Hoshq, RealLeo, Hbdragon88, Hotshot977, GregorB, Sega381, Petwil, Ae7flux, BD2412, Seb-Gibbs, Canderson7, Rjwilmsi, Rogerd, Zbxgscqf, Crazyvas, Fujiyama17, PCStuff, Vegaswikian, ABot, NeonMerlin, Zephlon, Bubba73, Ohanian, Sango123, Srleffler, OpenToppedBus, Imnotminkus, SusanneOberhauser, Antilived, Dkg, Scoo, Jasabella, YurikBot, Stujoe, Splette, Hydrargyrum, Chensiyuan, Gaius Cornelius, Rsrikanth05, Bloodofox, Nick, Jamesd, Santaduck, Voidxor, ManoaChild, Shotgunlee, Ben Lunsford, Wknight94, Mugunth Kumar, Novasource, Tokai, Closedmouth, Shawnc, Kevin, Fourohfour, X-mass, Kansaikiwi, Thomas Blomberg, NeilN, Nick-D, KnightRider~enwiki, SmackBot, Joeygil, Martin.Budden, Marc Lacoste, McGeddon, Müslimix, Rmosler2100, Chris the speller, Jkruis, SynergyBlades, Ctrlfreak13, Victorgrigas, DHN-bot~enwiki, Redline, Kimwx.zhou, Rarelibra, TobiWanKenobi~enwiki, Pete Fenelon, Trailbum, Hl, Djof, Matthew hk, Autopilot, Liem, Rklawton, JethroElfman, Roguegeek, Pomakis, Tlesher, Hotblaster, Fac Id, Dicklyon, Bashari, Dr.K., Simon Solts, Joseph Solis in Australia, Casull, Spudstud, Blehfu, Marysunshine, Atomobot, Jtnt, Owen214, Thetrick, CmdrObot, Raysonho, Jamoche, NickW557, Seven of Nine, Ameyjw, Samuell, 663highland, Fbello~enwiki, Van- Wiel, Myscrnnm, Lofote, Christian75, Avi4now, Archange56, Kozuch, Thijs!bot, TonyTheTiger, Bobo159, Barryfitzgerald, Grayshi, Klausness, Stybn, Arn7, Gioto, Widefox, Clintheacock66, Superzohar, Znkp, JAnDbot, Dogru144, The Transhumanist, Toutoune25, Ma- gioladitis, Bongwarrior, VoABot II, Michael Goodyear, Crmtm, Johnbibby, Japo, Erichfriedman, Oicumayberight, Nasa62, Jim.henderson, CommonsDelinker, J.delanoy, Herbythyme, Thegreenj, Giligone, Tiberius47, RenniePet, M-le-mot-dit, Althepal, Uthu, WIDEnet, Board- inbob, VolkovBot, Phasma Felis, Jfordhay, Benjamin Barenblat, DrSlony, Hkultala, Sam729, BwDraco, Schiec, Watchtherocks, Fal- con8765, Typ932, Yop83, Vitz-RS, MurderWatcher1, GavinTing, - tSR - Nth Man, Motorrad-67, SieBot, Jauerback, Unregistered.coward, Soler97, Davidyeotb, Ddxc, Marcela8an, Thunderkucing, Grassfire, ImageRemovalBot, Lethesl, Twinsday, ClueBot, Watto star, Nebrot, Wispanow, Buonaparte69, Razorflame, Ulysses370, ChrisHodgesUK, Markscape, Hewcanon, DumZiBoT, Happypoems, XLinkBot, Mister Macro, WikiSAF, Rror, Digitalfuture, Verandert, Osarius, Addbot, Oxtb3~enwiki, LPfi, Micahmedia, Cantaloupe2, West.andrew.g, Xyz42, Tassedethe, Lightbot, Vedran V, Zorrobot, Jemcgarvey, Pineapplejunkey, Luckas-bot, Yobot, Ptbotgourou, TheJammingYam, Petro2000, Nallimbot, AnomieBOT, Ta2Ed, Hinkelstein, Dramamoose, Materialscientist, Bernardos70, The High Fin Sperm Whale, Pitke, , LilHelpa, Xqbot, Imehling, GrouchoBot, R69S, Mark Schierbecker, SCΛRECROW, Shadowjams, Sliderpro, FrescoBot, LucienBOT, And i was a kaleidoscope, Stefano89, Citation bot 1, Gnepets, Rudolfo42, Aktabo, CameraPHD, Satellite779, Rettens2, KevinTjan, Fayedizard, Pinova, Reflexology, Mean as custard, Teravolt, EmausBot, John of Reading, WikitanvirBot, Angrytoast, Steroid Maximus, GoingBatty, Wikipelli, Dcirovic, GianoM, Fixblor, Jimharmer, Mihai.ile, Bamyers99, Shihan07, Gsarwa, Donner60, Sky- walkerPL, ClueBot NG, Wikiwierdo55, Matthiaspaul, Catlemur, BroderickAU, Frietjes, Praveen3530, Widr, Lebowbowbowski, Vick- yand30, BG19bot, Jeffrey M Dean, TheGeneralUser, Canoe1967, Ender1971, Soerfm, MonkeyKingBar, Normwiki, Glacialfox, Alina olya, BattyBot, EchoedZephyr, ChrisGualtieri, Tagremover, DoctorKubla, Mogism, Cerabot~enwiki, Retroxedits, Reatlas, Zalunardo8, Limefrost Spiral, BZillaGorilla, Tkom25022, Erickontena, Andrea edits, Bplcee, Skr15081997, Dslrweek, Monkbot, Andicbair, Delilah Grams, GeorginaMat, Modernswordsmith, Akimizu, Sophiacruz, GlottalFricative, CAPTAIN RAJU, Thomasadams1, Darshank641, In- ternetArchiveBot, Boomer Vial, AndyK2656, Prashant.jadon2, Silent Dick and Anonymous: 450 • CMOS Source: https://en.wikipedia.org/wiki/CMOS?oldid=763786864 Contributors: AxelBoldt, Taw, Mudlock, Heron, Nixdorf, Tan- nin, Ixfd64, Dori, Egil, Kaeslin, Julesd, Glenn, Harvester, Rick.G, Lenaic, Timwi, Mbstone, Chatool, Bemoeial, Wikiborg, Zoicon5, Mrand, Omegatron, Gerard Czadowski, Raul654, Robbot, Hankwang, Jakohn, Boffy b, RedWolf, Altenmann, Wikibot, Bdiddy, Iain.mcclatchie, Jleedev, Alan Liefting, David Gerard, Ancheta Wis, DocWatson42, DavidCary, Mintleaf~enwiki, Fleminra, Curps, NeoJustin, Rchan- dra, Richard cocks, Tagishsimon, Anoopm, Rdsmith4, Zondor, Mike Rosoft, Regex~enwiki, Andros 1337, Mjpieters, Mani1, Plugwash, Kwamikagami, Hayabusa future, Shadow demon, Sietse Snel, Duk, R. S. Shaw, Matt Britt, Towel401, Hooperbloob, Kolberg~enwiki, Storm Rider, Alansohn, EvanGrim, Atlant, Craigy144, Fritzpoll, Benefros, Velella, Wtshymanski, R6MaY89, Gene Nygaard, Voxadam, Akidd dublin, Nuno Tavares, Camw, CPES, TrentonLipscomb, Marudubshinki, MassGalactusUniversum, RxS, Snafflekid, Rjwilmsi, Arisa, Maxim Razin, Firebug, FlaBot, Mirror Vax, Arnero, Nimur, Chobot, Cactus.man, Siddhant, YurikBot, RobotE, Hairy Dude, Arado, Koffieyahoo, Jengelh, Toffile, Shaddack, Schoen, Bmdavll, JulesH, Prolineserver, TERdON, Voidxor, Zwobot, BOT-Superzerocool, DeadEyeArrow, Zzuuzz, Luethi, Gaurav., Niclinley, Cmglee, Nick R Hill, SmackBot, Smitz, Hydrogen Iodide, Jab843, DreamOfMir- rors, Amux, Gspbeetle, Oli Filth, Sadads, Simpsons contributor, Huangjs~enwiki, Burns flipper, JonHarder, Flyguy649, Eran of Arcadia, Reza mirhosseini, Hkmaly, SashatoBot, Rory096, Jaganath, Jamesm76, Vanished user 8ij3r8jwefi, Slakr, Robert Bond, Dicklyon, Hu12, Emote, Sakurambo, Makeemlighter, Circuit dreamer, Hypersw, Casper2k3, Cyferz, Thijs!bot, Epbr123, AntiVandalBot, Majorly, Wide- fox, MsDivagin, Rico402, JAnDbot, Deflective, Arch dude, PhilKnight, VoABot II, Ethan a dawe, Refael Ackermann, Fulvius~enwiki, MartinBot, Mmoneypenny, Manavbhardwaj, KarBOT, Ctroy36, J.delanoy, Martinor, Helon, Mintz l, Shervin moloudi, Zen-in, Rod57, Chriswiki, Uthu, Useight, ThePointblank, Jakejuliebaker, ICE77, Jeff G., AlnoktaBOT, VasilievVV, Franck Dernoncourt, TXiKiBoT, Zidonuke, Leafyplant, Ilyushka88, SieBot, Wing gundam, 18jahremädchen, Jp314159, Flyer22 Reborn, R J Sutherland, Lightmouse, Spit- fire19, Reneeholle, StaticGull, Mygerardromance, Jbw2, Vcaeken, ClueBot, The Thing That Should Not Be, CounterVandalismBot, Brews ohare, Iohannes Animosus, Crazy Boris with a red beard, Wg3v07, Rror, Ost316, Alexius08, Addbot, Mortense, Download, Glane23, Debresser, Mraiford, Ericg33, Semiwiki, Tide rolls, Lightbot, Krano, Zorrobot, Jarble, Ben4, Luckas-bot, Yobot, OrgasGirl, Ptbotgourou, II MusLiM HyBRiD II, Yuejian, AnomieBOT, Piano non troppo, CiLiNDr0, LiuyuanChen, Materialscientist, Luen, Xqbot, Ywaz, Ed- win.jacob, Millahnna, Wdl1961, Trurle, RibotBOT, Shadowjams, A.amitkumar, Vinay.mullerpaten, Prari, Ijwofawx, Pshent, A8UDI, Wikitanvir, Dantzig~enwiki, Copio, Sweerran, Weedwhacker128, Jfmantis, Mean as custard, Alph Bot, Aircorn, Slightsmile, Dcirovic, Checkingfax, Allforrous, Wayne Slam, Cinnanom, Diamondland, Mikhail Ryazanov, ClueBot NG, Jnorton7558, Manrajgujral, Widr, Danim, JordoCo, Heartinpiece, ProWin, Rbfoster2, Morganson691, ChrisGualtieri, Abcd temp abcd, Dexbot, Webclient101, Mkostya, Mile47, Epicgenius, Aselzer3, Mithoon, Photonis, Sheldon.andre, Nuetural, Jamajhinx06, WenDMAKN, Ausrapeka and Anonymous: 365 • Active pixel sensor Source: https://en.wikipedia.org/wiki/Active_pixel_sensor?oldid=757339373 Contributors: Julesd, Glenn, Bearcat, Bkell, David Gerard, Giftlite, Quadell, Diamonddavej, Wrs1864, Kocio, Wtshymanski, Nightstallion, Rjwilmsi, Chobot, Petri Krohn, Cmglee, SmackBot, Marc Lacoste, Mdd4696, Chris the speller, Ctrlfreak13, Octahedron80, Pkomma, A5b, Bcasterline, Dicklyon, Peter Horn, Hu12, Geremia, MattCohen, LG4761, Farahead, Gioto, Widefox, DeliDumrul, TAnthony, Jllm06, Mr.noe, Jadedcrypto, Jim.henderson, Ericfossum, Funandtrvl, NathanHagen, AlleborgoBot, VVVBot, Npd2983, ClueBot, Starvinsky, Mild Bill Hiccup, Cold- north, Hanathan, Addbot, Mathieu Perrin, Kelly, DOI bot, Luckas-bot, Yobot, DiverDave, Gargan26, Citation bot, Stevebow, Omni- paedista, Pluisjenijn, Filya1, Citation bot 1, RedBot, Trappist the monk, Chad1994, RjwilmsiBot, Andronymous, Dannydayus, Will Beback Auto, CocuBot, Helpful Pixie Bot, Bibcode Bot, BattyBot, ChrisGualtieri, Koza1983, Stub Mandrel, Monkbot, PhotoInt, EricR- 11.1. TEXT 199

Fossum, Dorivaldo de C. M. dos Santos, Thisshouldbenew, InternetArchiveBot, Chroble and Anonymous: 71 • Charge-coupled device Source: https://en.wikipedia.org/wiki/Charge-coupled_device?oldid=763919960 Contributors: Bryan Derksen, AstroNomer, LA2, Carpentis, Roadrunner, DrBob, Heron, JohnOwens, Michael Hardy, Pit~enwiki, Liftarn, Rambot, Dcljr, Islandboy99, MichaelJanich, Alfio, Egil, Ahoerstemeier, WeißNix, Glenn, RadRafe, Pizza Puzzle, Epo~enwiki, Agtx, RodC, Chatool, Nv8200pa, Omegatron, Rnbc, Carbuncle, Robbot, Fredrik, Altenmann, Lowellian, Roscoe x, Jondel, Hadal, Wikibot, Iain.mcclatchie, David Gerard, Giftlite, Andries, DavidCary, Seabhcan, BenFrantzDale, Laurens~enwiki, Levin, Average Earthman, Fleminra, Hugh2414, Nayuki, Pin- necco, Toytoy, ConradPino, Beland, EricKerby, GeoGreg, Sam Hocevar, Ianneub, Hugh Mason, Deglr6328, DMG413, Grunt, Stevenmat- tern, Imroy, JTN, Blanchette, Discospinster, Brianhe, ArnoldReinhold, Mani1, Night Gyr, Bender235, Kbh3rd, MisterSheik, Bobo192, Zwilson, LuoShengli, Kjkolb, Hooperbloob, Nsaa, Passw0rd, Jhfrontz, Alansohn, Arthena, Ksnow, Fourthords, Wtshymanski, Cburnett, Dtcdthingy, ComCat, DV8 2XL, Algocu, Zzen, Forderud, Forteblast, Stuartyeates, Kelly Martin, Jacobolus, Pierstitus, Eyreland, Kral- izec!, Pfalstad, Paxsimius, Rnt20, Graham87, NubKnacker, Eteq, Nanite, Coneslayer, Ae77, Jehochman, Azure8472, FlaBot, Arnero, Margosbot~enwiki, RexNL, SkiDragon, Srleffler, Chobot, Stoive, John Dalton, YurikBot, Arado, Toffile, Hogghogg, Gaius Cornelius, Shaddack, Megastar, Jeword, NawlinWiki, Spike Wilbury, Długosz, Diotti, TDogg310, Marky1124, Alex43223, Zwobot, Kkmurray, SSN21, Jwissick, Petri Krohn, Mike1024, JLaTondre, GrinBot~enwiki, Shahram 77, Victor falk, Attilios, SmackBot, Ashenai, Brian Pa- trie, Reedy, Marc Lacoste, Verne Equinox, Stefan506, Liaocyed, Zephyris, Gilliam, Vwatts, BrynJones216, Lindosland, Kurykh, Snori, Oli Filth, Scawt, Octahedron80, DHN-bot~enwiki, Hongooi, Hgrosser, Rrburke, VMS Mosaic, RandomWalker, Andrei Stroe, JorisvS, Hillelg, MarkSutton, Dicklyon, Mets501, Peter Horn, Hu12, JMK, Sharkiedog, AmberRobot, Zyphane, Albester, Cydebot, A876, Sem- pai, MattCohen, Wikid77, JKW~enwiki, Headbomb, Electron9, Khened, Stybn, AntiVandalBot, Kennethmaage, Edokter, Yellowdesk, Drake Wilson, Amberroom, JAnDbot, CombatWombat42, The Transhumanist, SiobhanHansa, Astrofitz, Massive hair, Email4mobile, Sstolper, The Kinslayer, Dpser, Caffeine USA, BilCat, David Eppstein, User A1, DerHexer, Gphoto, Hoffes2, Jim.henderson, Elauer, R'n'B, CommonsDelinker, Nono64, Ctroy36, Mausy5043, Nev1, Merzperson, Akinoame, Tarotcards, Myrin1, Nwbeeson, KylieTastic, Cometstyles, JavierMC, Indie Film, Idioma-bot, Funandtrvl, VolkovBot, NathanHagen, Vipinhari, Andormarketing, C-M, Dfbaum, Spin- ningspark, SieBot, Aeranis, Mvadu, Milanfrazer, ASEEMASEEM, Chem-awb, ImageRemovalBot, ClueBot, Cambrasa, Robenel, Qw- ertylex, Stargazer 7000~enwiki, Yuckhil, Excirial, Brews ohare, Manderson198, DumZiBoT, Nigel 2008, Rror, Wikiuser100, Printz150, Nepenthes, Tubesship, Addbot, Mathieu Perrin, Olli Niemitalo, Hosse~enwiki, Download, LaaknorBot, Janeclimber, LinkFA-Bot, Kak- tus Kid, Tide rolls, Lightbot, Rojypala, Margin1522, Yobot, Ptbotgourou, Ghasem.nejati, Aldebaran66, Jason Recliner, Esq., Thzatheist, Auxeo, AnomieBOT, Brandoisbatman, Powwradota, Ecodeluz, The Lamb of God, Mrblue23, Materialscientist, Northryde, Corrigendas, DSisyphBot, Idegmcsa, Twirligig, Coosbane, Pluisjenijn, Fotaun, FrescoBot, Tobby72, Falling style, Steve Quinn, Stevansan, Citation bot 1, Pinethicket, Noso1, Lingust, RedBot, Akalabeth, Enemenemu, Aghagolm, Chad1994, Moizoo, SmozBleda, RjwilmsiBot, Nihola, John of Reading, Nuujinn, Dewritech, Solarra, Dcirovic, Apogee3, AvicBot, John Cline, Іванко1, Donner60, Paileboat, Will Beback Auto, ClueBot NG, Natural Philo, Frietjes, JordoCo, Rrudzik, Rainbow in the Dark, Mtompsett, Helpful Pixie Bot, Bibcode Bot, BG19bot, Varunbs1, Badon, Ytpete, Andrzej w k 2, Soerfm, David.moreno72, ChrisGualtieri, Tagremover, Dexbot, S Osseir, Tom Toyosaki, Insti- tutionilized, Mejbp, Lemnaminor, Binarysequence, Eyesnore, Koza1983, Ugog Nizdast, Dough34, GabrielleNÜVÜ, Aransfak, Cpt Wise, InternetArchiveBot, , GreenC bot, Gulumeemee, Superchunk22, VeritasLaureate and Anonymous: 341 • Shutter (photography) Source: https://en.wikipedia.org/wiki/Shutter_(photography)?oldid=758604407 Contributors: Mulad, Jleedev, Christopherlin, Imroy, Helohe, Barcex, Hooperbloob, Yhr, HenryLi, Carcharoth, Pol098, Dysepsion, Josh Parris, Clerambj~enwiki, The wub, Bbullot~enwiki, Mahlum~enwiki, Srleffler, Roboto de Ajvol, Hede2000, Hellbus, Gaius Cornelius, Stassats, Mirko Raner, Staxringold, SmackBot, Yamaguchi, Chris the speller, Sim man, Arnob1, Radagast83, ILike2BeAnonymous, Dicklyon, INkubusse, Thijs!bot, JAnDbot, Cocytus, Jim.henderson, CommonsDelinker, Adavidb, Being blunt, Adam Zivner, VolkovBot, Abtinb, Max.goedjen, SieBot, ClueBot, Hustvedt, Wikit2007, KLWhitehead, Little Mountain 5, Addbot, NikOly, Luckas-bot, Yobot, Underthedial, Magog the Ogre, Redbobblehat, Materialscientist, ArthurBot, GrouchoBot, , RibotBOT, SassoBot, Nightsturm, Keegscee, EmausBot, Cogiati, Gsarwa, Puffin, ChuispastonBot, Socialservice, ClueBot NG, K0 7zQY0oyqcz, BG19bot, Darafsh, Frze, Jaclu, Thegreatgrabber, AntanO, Fluffystar, ChrisGualtieri, Avian appreciator, Toma.preidyte and Anonymous: 54 • Mode dial Source: https://en.wikipedia.org/wiki/Mode_dial?oldid=587726100 Contributors: Musiphil, Pol098, KymFarnik, Ceinturion, Rwalker, OrphanBot, Mojo Hand, Widefox, Fetchcomms, Jim.henderson, Althepal, TXiKiBoT, UrSuS, ImageRemovalBot, Jeroen74~enwiki, Addbot, Luckas-bot, Foma39, FrescoBot, Matthiaspaul, ChrisGualtieri and Anonymous: 9 • Digital camera modes Source: https://en.wikipedia.org/wiki/Digital_camera_modes?oldid=758233600 Contributors: Jpk, Mattdm, Club- marx, Pol098, WadeSimMiser, KymFarnik, Mandarax, Bubba73, SmackBot, CSZero, SmackEater, Nbarth, Kozuch, PhilKnight, Jim.henderson, Althepal, BwDraco, Martinangel, Twinsday, Mild Bill Hiccup, Vybr8, Rror, WikHead, Wikipelli, Gsarwa, Widr, U-95 and Anonymous: 17 • Shutter priority Source: https://en.wikipedia.org/wiki/Shutter_priority?oldid=676390411 Contributors: Kricke, Seano1, Girolamo Savonarola, Mattdm, Hooperbloob, Fawcett5, The wub, Avocado, Srleffler, YurikBot, Rwalker, SmackBot, Ale jrb, Widefox, Ekabhishek, HowardLive, Althepal, Mcewan, Jeroen74~enwiki, Stonewhite, Addbot, SpBot, Dewil, Luckas-bot, Yobot, Raviaka Ruslan, AnomieBOT, The High Fin Sperm Whale, Erik9bot, Lopifalko, Mehdi, ClueBot NG, JYBot, Sfgiants1995 and Anonymous: 13 • Aperture priority Source: https://en.wikipedia.org/wiki/Aperture_priority?oldid=731002868 Contributors: SebastianHelm, Kricke, Mor- ven, Tea2min, Enochlau, MarkSweep, Mindmatrix, Bubba73, The wub, Avocado, FlaBot, Srleffler, Manop, SmackBot, Chych, Nbarth, Can't sleep, clown will eat me, Herd of Swine, ForrestCroce, PhiLiP, Widefox, Charles01, Ptr ru, Maverickapollo, Althepal, STBotD, Jacobsn, The Nature Guy, Legoktm, SieBot, Twinsday, Jeroen74~enwiki, Addbot, Dewil, Gyro Copter, Raviaka Ruslan, Rubinbot, The High Fin Sperm Whale, Erik9bot, Craig Pemberton, , Tbhotch, Lopifalko, Mehdi, ClueBot NG, Matthiaspaul, AdventurousSquirrel, JYBot, EstherSmarts and Anonymous: 17 • Sensitivity priority Source: https://en.wikipedia.org/wiki/Sensitivity_priority?oldid=368319102 Contributors: KymFarnik, Nbarth and TotientDragooned • Bayer filter Source: https://en.wikipedia.org/wiki/Bayer_filter?oldid=746722647 Contributors: The Anome, Egil, Fibonacci, Ed g2s, Samsara, Dale Arnett, Boffy b, Carnildo, David Gerard, Pavon, Jeremiah, Giftlite, Dbenbenn, Zigger, Jason Quinn, Christopherlin, Wma- han, Toytoy, Girolamo Savonarola, Mmj, Abdull, Moxfyre, Stevenmattern, Imroy, Rich Farmbrough, Smalljim, Mdd, Interiot, DreamGuy, Cburnett, Ori Idan, Skor, Jacobolus, Abu ari, Bluemoose, Plowboylifestyle, Pfalstad, Ashmoo, TAKASUGI Shinji, Snafflekid, Rjwilmsi, Cambridgeincolour, Gareth McCaughan, Bubba73, Gary Brown, Efficacy, NekoDaemon, Quuxplusone, GreyCat, Srleffler, Bgwhite, Jachin, Gaius Cornelius, Richard Allen, Długosz, Darkfred, Kkmurray, Ilmari Karonen, SDS, Cmglee, TuukkaH, SmackBot, Incnis Mrsi, Marc Lacoste, Betacommand, Nbarth, Kostmo, Hgrosser, Racklever, VMS Mosaic, Tomtefarbror, Aditsu, Dicklyon, Monni95, Quibik, Papuass, Widefox, Gumby600, Big oaf, GermanX, LiamUK, Jim.henderson, MichaelStanford, Michael Frind, SieBot, Janggeom, Wdwd, 200 CHAPTER 11. TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

Moesey, Sesameball, Rror, Addbot, Hosse~enwiki, Da5nsy, SpBot, Zorrobot, Luckas-bot, Yobot, KamikazeBot, ArthurBot, S.mackesey, Oashi, Citation bot 1, Rc3002, Rayshade, Hgb asicwizard, Tuankiet65, ZéroBot, DisplayGeek, Ὁ οἶστρος, H3llBot, Frietjes, Helpful Pixie Bot, Khazar2, Fyodorser, Saung Tadashi, Mogism, Debayer, Monkbot, Sh Hannes, Aitorninerola, Mithuha, Jonathan Ben-Avraham, InternetArchiveBot, GreenC bot, Bender the Bot, Paul oz and Anonymous: 48 • Color filter array Source: https://en.wikipedia.org/wiki/Color_filter_array?oldid=759755491 Contributors: Ugen64, GreatWhiteNorth- erner, David Gerard, Giftlite, Imroy, Cburnett, Abu ari, Prashanthns, Rjwilmsi, Srleffler, Adoniscik, Kkmurray, SmackBot, Martin.Budden, Rmosler2100, Wuffyz, A5b, Dicklyon, Credema, Midgrid, JaGa, GermanX, R'n'B, J.delanoy, Kurtrosenfeld, TXiKiBoT, Tresiden, Moe- sey, Bob1960evens, Rror, Addbot, Lightbot, Qkowlew, AnomieBOT, Kingpin13, Citation bot, LilHelpa, LucienBOT, Citation bot 1, Jonesey95, Ztronix, TobeBot, Dcirovic, ClueBot NG, Helpful Pixie Bot, Debouch, Monkbot, Filedelinkerbot, InternetArchiveBot, Ben- der the Bot and Anonymous: 38

11.2 Images

• File:001_a01_camera_obscura_abrazolas.jpg Source: https://upload.wikimedia.org/wikipedia/commons/e/ec/001_a01_camera_obscura_ abrazolas.jpg License: Public domain Contributors: file:///C:/magical%20motion%20museum/00%20pre-lanterna%20magica/camera% 20obscura/001_a01_camera_obscura_abrazolas..jpg Original artist: Unknownwikidata:Q4233718 • File:1292(or_earlier)_roger_bacon_-_image006.jpg Source: https://upload.wikimedia.org/wikipedia/commons/3/38/1292%28or_earlier% 29_roger_bacon_-_image006.jpg License: Public domain Contributors: http://www.bonnerweb.de/bilder/pinhole/sonnentaler/sonnentalerdateien/ image006.jpg Original artist: Roger Bacon? • File:1545_gemma_frisius_-_camera-obscura-sonnenfinsternis_1545-650x337.jpg Source: https://upload.wikimedia.org/wikipedia/ commons/4/4d/1545_gemma_frisius_-_camera-obscura-sonnenfinsternis_1545-650x337.jpg License: Public domain Contributors: http: //blog.staedelmuseum.de/wp-content/uploads/2012/07/camera-obscura-sonnenfinsternis_1545-650x337.jpg Original artist: Leonardo da Vinci • File:16-04-09_Nikon_F5_RalfR_WAT_6948.jpg Source: https://upload.wikimedia.org/wikipedia/commons/6/6d/16-04-09_Nikon_ F5_RalfR_WAT_6948.jpg License: GFDL 1.2 Contributors: Own work Original artist: Ralf Roletschek • File:1619_Scheiner_-_Oculus_hoc_est_(frontispiece).jpg Source: https://upload.wikimedia.org/wikipedia/commons/4/41/1619_Scheiner_ -_Oculus_hoc_est_%28frontispiece%29.jpg License: Public domain Contributors: unknown Original artist: Christoph Scheiner • File:1636_Daniel_Schwenter_-_Deliciae_Physico-Mathematicae_(scioptic_ball).jpg Source: https://upload.wikimedia.org/wikipedia/ commons/9/97/1636_Daniel_Schwenter_-_Deliciae_Physico-Mathematicae_%28scioptic_ball%29.jpg License: Public domain Contrib- utors: https://play.google.com/books/reader?id=EWM_AAAAcAAJ&printsec=frontcover&output=reader&hl=en_GB&pg=GBS.PA254 Original artist: Daniel Schwenter • File:1642_Mario_Bettini_-_Apiaria_universae_philosophiae_mathematica.jpg Source: https://upload.wikimedia.org/wikipedia/commons/ a/a0/1642_Mario_Bettini_-_Apiaria_universae_philosophiae_mathematica.jpg License: Public domain Contributors: http://www.arauco. org/SAPEREAUDE/optica/camaraoscura/imgs/formacionimagenes/Camera%20Obscura,%20dans%20-%20Mario%20Bettinig.jpg Orig- inal artist: Mario Bettini • File:1646_Athanasius_Kircher_-_Camera_obscura.jpg Source: https://upload.wikimedia.org/wikipedia/commons/8/85/1646_Athanasius_ Kircher_-_Camera_obscura.jpg License: Public domain Contributors: http://web.stanford.edu/group/kircher/cgi-bin/site/wp-content/ uploads/kircher_1281.jpg Original artist: Athanasius Kircher • File:1676_Johann_Sturm_-_Camerae_Obscurae_Portatilis.jpg Source: https://upload.wikimedia.org/wikipedia/commons/4/42/1676_ Johann_Sturm_-_Camerae_Obscurae_Portatilis.jpg License: Public domain Contributors: https://books.google.nl/books?id=nbMWAAAAQAAJ& printsec=frontcover#v=onepage&q&f=false Original artist: Johann Sturm • File:1858_-_Gagniet_(d)_Quarteley_(g)_-_Cours_de_Physique_(A._Ganot).jpg Source: https://upload.wikimedia.org/wikipedia/ commons/d/d0/1858_-_Gagniet_%28d%29_Quarteley_%28g%29_-_Cours_de_Physique_%28A._Ganot%29.jpg License: Public do- main Contributors: https://drawingmachines.org/post.php?id=111 Original artist: Gagniet (drawing) J. Ouartley (woodcut) • File:2-TFT-APS-PPS.svg Source: https://upload.wikimedia.org/wikipedia/commons/7/74/2-TFT-APS-PPS.svg License: Public do- main Contributors: Own work Original artist: Gargan • File:2.1_MP_CCD_Close_Up.JPG Source: https://upload.wikimedia.org/wikipedia/commons/3/34/2.1_MP_CCD_Close_Up.JPG Li- cense: CC BY 3.0 Contributors: Own work (Original text: self-made) Original artist: Qwertylex (talk) • File:A_deep_infrared_view_of_the_Orion_Nebula_from_HAWK-I.jpg Source: https://upload.wikimedia.org/wikipedia/commons/ a/ae/A_deep_infrared_view_of_the_Orion_Nebula_from_HAWK-I.jpg License: CC BY 4.0 Contributors: http://www.eso.org/public/ images/eso1625a/ Original artist: ESO/H. Drass et al. • File:A_micrograph_of_the_corner_of_the_photosensor_array_of_a_‘webcam’. Source: https://upload.wikimedia.org/wikipedia/ commons/e/ef/A_micrograph_of_the_corner_of_the_photosensor_array_of_a_%E2%80%98webcam%E2%80%99.jpeg License: CC BY-SA 3.0 Contributors: Own work Original artist: Natural Philo • File:Absorption-X3.svg Source: https://upload.wikimedia.org/wikipedia/commons/9/9d/Absorption-X3.svg License: CC BY 3.0 Con- tributors: Based on File:Absorption-X3.png. SVG-Drawing: Own work Original artist: wdwd • File:Acap.svg Source: https://upload.wikimedia.org/wikipedia/commons/5/52/Acap.svg License: Public domain Contributors: Own work Original artist: F l a n k e r • File:Ambox_important.svg Source: https://upload.wikimedia.org/wikipedia/commons/b/b4/Ambox_important.svg License: Public do- main Contributors: Own work, based off of Image:Ambox scales.svg Original artist: Dsmurat (talk · contribs) 11.2. IMAGES 201

• File:An_RGGB_Bayer_Colour_Filter_on_a_1980’{}s_vintage_Sony_PAL_Camcorder_CCD.png Source: https://upload.wikimedia. org/wikipedia/commons/7/78/An_RGGB_Bayer_Colour_Filter_on_a_1980%27s_vintage_Sony_PAL_Camcorder_CCD.png License: CC BY-SA 3.0 Contributors: Own work Original artist: Binarysequence • File:Aperture_priority_mode.svg Source: https://upload.wikimedia.org/wikipedia/commons/6/69/Aperture_priority_mode.svg License: CC BY-SA 2.5 Contributors: ModeDial.svg Original artist: • Graphic: Althepal • File:Aps_pd_pixel_schematic.svg Source: https://upload.wikimedia.org/wikipedia/commons/2/20/Aps_pd_pixel_schematic.svg License: Public domain Contributors: Own work Original artist: Gargan • File:ArgusCCD.jpg Source: https://upload.wikimedia.org/wikipedia/en/9/94/ArgusCCD.jpg License: PD Contributors: Own work Original artist: Merzperson (talk)(Uploads) • File:Arri_Alexa_camera.jpg Source: https://upload.wikimedia.org/wikipedia/commons/b/ba/Arri_Alexa_camera.jpg License: CC BY 2.0 Contributors: Arri Alexa Original artist: Sean P. Anderson from Dallas, TX, USA • File:Asahiflex600.jpg Source: https://upload.wikimedia.org/wikipedia/commons/f/f1/Asahiflex600.jpg License: Attribution Contribu- tors: Transferred from en.wikipedia to Commons. Original artist: The original uploader was Jeff dean at English Wikipedia • File:Aspect-ratio-16x9.svg Source: https://upload.wikimedia.org/wikipedia/commons/f/f8/Aspect-ratio-16x9.svg License: Public do- main Contributors: own work, manual SVG coding Original artist: Jerzy Jalocha N • File:Aspect-ratio-3x2.svg Source: https://upload.wikimedia.org/wikipedia/commons/8/8c/Aspect-ratio-3x2.svg License: Public do- main Contributors: own work, manual SVG coding Original artist: Jerzy Jalocha N • File:Aspect-ratio-4x3.svg Source: https://upload.wikimedia.org/wikipedia/commons/d/de/Aspect-ratio-4x3.svg License: Public do- main Contributors: own work, manual SVG coding Original artist: Tanya sanderson • File:Bayer_pattern.svg Source: https://upload.wikimedia.org/wikipedia/commons/3/3c/Bayer_pattern.svg License: CC-BY-SA-3.0 Con- tributors: Own work Original artist: Cburnett • File:Bayer_pattern_on_sensor.svg Source: https://upload.wikimedia.org/wikipedia/commons/3/37/Bayer_pattern_on_sensor.svg Li- cense: CC-BY-SA-3.0 Contributors: This vector image was created with Inkscape. Original artist: en:User:Cburnett • File:Bayer_pattern_on_sensor_profile.svg Source: https://upload.wikimedia.org/wikipedia/commons/1/1c/Bayer_pattern_on_sensor_ profile.svg License: CC-BY-SA-3.0 Contributors: This vector image was created with Inkscape. Original artist: en:User:Cburnett • File:Blooming_ccd.jpg Source: https://upload.wikimedia.org/wikipedia/commons/9/91/Blooming_ccd.jpg License: Public domain Con- tributors: Self-photographed Original artist: Hungerhirn • File:CCD_SONY_ICX493AQA_pins_side.jpg Source: https://upload.wikimedia.org/wikipedia/commons/1/1e/CCD_SONY_ICX493AQA_ pins_side.jpg License: CC BY-SA 4.0 Contributors: Own work Original artist: Andrzej w k 2 • File:CCD_SONY_ICX493AQA_sensor_side.jpg Source: https://upload.wikimedia.org/wikipedia/commons/5/5b/CCD_SONY_ICX493AQA_ sensor_side.jpg License: CC BY-SA 4.0 Contributors: Own work Original artist: Andrzej w k 2 • File:CCD_charge_transfer_animation.gif Source: https://upload.wikimedia.org/wikipedia/commons/6/66/CCD_charge_transfer_animation. gif License: CC BY 2.5 Contributors: animated drawing created myself Original artist: Michael Schmid • File:CCD_line_sensor.JPG Source: https://upload.wikimedia.org/wikipedia/commons/3/30/CCD_line_sensor.JPG License: CC-BY- SA-3.0 Contributors: Own work Original artist: Stefan506 (dewiki userpage) • File:CMOS_Inverter.svg Source: https://upload.wikimedia.org/wikipedia/commons/8/81/CMOS_Inverter.svg License: Public domain Contributors: Own drawing, Inkscape 0.43 Original artist: inductiveload • File:CMOS_NAND.svg Source: https://upload.wikimedia.org/wikipedia/commons/e/e2/CMOS_NAND.svg License: CC BY-SA 3.0 Contributors: Own work Original artist: JustinForce • File:CMOS_NAND_Layout.svg Source: https://upload.wikimedia.org/wikipedia/commons/8/8f/CMOS_NAND_Layout.svg License: Public domain Contributors: Transferred from en.wikipedia to Commons. Original artist: Jamesm76 at English Wikipedia • File:CMOS_fabrication_process.svg Source: https://upload.wikimedia.org/wikipedia/commons/5/57/CMOS_fabrication_process.svg License: CC BY-SA 3.0 Contributors: Own work Original artist: ? • File:CYGM_pattern.svg Source: https://upload.wikimedia.org/wikipedia/commons/5/53/CYGM_pattern.svg License: CC-BY-SA-3.0 Contributors: This vector image was created with Inkscape. Original artist: en:User:Cburnett • File:CYYM_pattern.svg Source: https://upload.wikimedia.org/wikipedia/commons/7/76/CYYM_pattern.svg License: CC-BY-SA-3.0 Contributors: edited from CYGM pattern.svg created by en:User:Cburnett Original artist: Sergej Qkowlew • File:Cam_06.jpg Source: https://upload.wikimedia.org/wikipedia/commons/7/74/Cam_06.jpg License: CC BY 2.5 Contributors: No machine-readable source provided. Own work assumed (based on copyright claims). Original artist: No machine-readable author provided. Dingemansm~commonswiki assumed (based on copyright claims). • File:Camara-obscura-image.JPG Source: https://upload.wikimedia.org/wikipedia/commons/c/c4/Camara-obscura-image.JPG License: Public domain Contributors: Own work Original artist: Code6840 • File:CameraObscura.JPG Source: https://upload.wikimedia.org/wikipedia/commons/5/5d/CameraObscura.JPG License: Public do- main Contributors: (Original text: Picture taken by Seth_Ilys (talk)(Uploads) on 23 April 2005 and released into the public domain.) Original artist: Seth_Ilys (talk)(Uploads) • File:CameraObscuraSanFranciscoCliffHouse.jpg Source: https://upload.wikimedia.org/wikipedia/en/b/b0/CameraObscuraSanFranciscoCliffHouse. jpg License: Cc-by-sa-3.0 Contributors: Own work Original artist: Ioerror (talk)(Uploads) 202 CHAPTER 11. TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• File:Camera_Obscura.JPG Source: https://upload.wikimedia.org/wikipedia/commons/6/62/Camera_Obscura.JPG License: CC BY- SA 3.0 Contributors: Mark Ellis Original artist: Saraplacid • File:Camera_Obscura_box18thCentury.jpg Source: https://upload.wikimedia.org/wikipedia/commons/f/fd/Camera_Obscura_box18thCentury. jpg License: Public domain Contributors: 19th Century Dictionary Illustration Original artist: unknown illustrator • File:Camera_Obscura_in_Use.JPG Source: https://upload.wikimedia.org/wikipedia/commons/1/1c/Camera_Obscura_in_Use.JPG Li- cense: CC BY-SA 3.0 Contributors: Own work Original artist: The Bearded Man • File:Camera_obscura.jpg Source: https://upload.wikimedia.org/wikipedia/commons/9/9f/Camera_obscura.jpg License: Public do- main Contributors: ? 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Original artist: The original uploader was Jeff dean at English Wikipedia • File:Crystal_Clear_device_camera.png Source: https://upload.wikimedia.org/wikipedia/commons/9/99/Crystal_Clear_device_camera. png License: LGPL Contributors: All Crystal Clear icons were posted by the author as LGPL on kde-look; Original artist: Everaldo Coelho and YellowIcon; • File:Cut-away_Minotla_SLR_IMG_0377.jpg Source: https://upload.wikimedia.org/wikipedia/commons/d/d1/Cut-away_Minotla_SLR_ IMG_0377.jpg License: CC BY-SA 2.0 fr Contributors: Own work Original artist: Rama • File:Cut-away_Minotla_SLR_IMG_0378.jpg Source: https://upload.wikimedia.org/wikipedia/commons/d/db/Cut-away_Minotla_SLR_ IMG_0378.jpg License: CC BY-SA 2.0 fr Contributors: Own work Original artist: Rama • File:DSLR_Liveview.jpg Source: https://upload.wikimedia.org/wikipedia/commons/e/ee/DSLR_Liveview.jpg License: CC BY-SA 3.0 Contributors: Pixel8 Original artist: © Bill Bertram (Pixel8) 2009 11.2. IMAGES 203

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Original artist: ? • File:Ice_Cream_Dreams,_by_Chris_Marchant.jpg Source: https://upload.wikimedia.org/wikipedia/commons/4/41/Ice_Cream_Dreams% 2C_by_Chris_Marchant.jpg License: CC BY 2.0 Contributors: https://www.flickr.com/photos/forayinto35mm/7381039510/ Original artist: Chris Marchant • File:Image_of_Russian-made_Zennit_without_lens_kit.jpg Source: https://upload.wikimedia.org/wikipedia/en/1/1a/Image_of_Russian-made_ Zennit_without_lens_kit.jpg License: CC-BY-4.0 Contributors: I shot my old SLR yesterday while testing my new batteries for my Nikon,(though Micromax was used to take this final shot) Previously published: None. Published nowhere else. Original artist: Jon Ascton 204 CHAPTER 11. TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• File:Image_sensor_and_motherbord_nikon_coolpix_l2.JPG Source: https://upload.wikimedia.org/wikipedia/commons/9/96/Image_ sensor_and_motherbord_nikon_coolpix_l2.JPG License: CC BY-SA 3.0 Contributors: Own work Original artist: Feudiable • File:Institut_Lumière_-_CINEMATOGRAPHE_Camera.jpg Source: https://upload.wikimedia.org/wikipedia/commons/0/0a/Institut_ Lumi%C3%A8re_-_CINEMATOGRAPHE_Camera.jpg License: CC BY-SA 4.0 Contributors: Own work Original artist: Victorgrigas • File:Kodak57b.jpg Source: https://upload.wikimedia.org/wikipedia/commons/9/90/Kodak57b.jpg License: CC-BY-SA-3.0 Contribu- tors: ? 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Original artist: Rnt20 at English Wikipedia • File:Pentax_K3_jm6729.jpg Source: https://upload.wikimedia.org/wikipedia/commons/9/9b/Pentax_K3_jm6729.jpg License: CC BY- SA 3.0 Contributors: Own work Original artist: user:joergens.mi • File:Pentax_Q_02n3000.jpg Source: https://upload.wikimedia.org/wikipedia/commons/a/a3/Pentax_Q_02n3000.jpg License: CC BY 2.5 Contributors: 663highland Original artist: 663highland • File:Pentax_super_me_open_back.gif Source: https://upload.wikimedia.org/wikipedia/commons/a/a9/Pentax_super_me_open_back. gif License: CC BY-SA 3.0 Contributors: Own work Original artist: Hustvedt • File:Pinhole-camera.svg Source: https://upload.wikimedia.org/wikipedia/commons/3/3b/Pinhole-camera.svg License: Public domain Contributors: http://commons.wikimedia.org/wiki/Image:Pinhole-camera.png Original artist: en:User:DrBob (original); en:User:Pbroks13 (redraw) 11.2. IMAGES 205

• File:PinholeCameraAndRelatedSupplies.jpg Source: https://upload.wikimedia.org/wikipedia/en/7/7d/PinholeCameraAndRelatedSupplies. jpg License: CC-BY-SA-2.5 Contributors: ? Original artist: ? • File:PinholeCameraImage.jpg Source: https://upload.wikimedia.org/wikipedia/commons/d/d5/PinholeCameraImage.jpg License: Pub- lic domain Contributors: Own work Original artist: Willspear1564 • File:Pinhole_hydrant_neg_pos.jpg Source: https://upload.wikimedia.org/wikipedia/commons/b/bd/Pinhole_hydrant_neg_pos.jpg Li- cense: CC BY-SA 2.5 Contributors: Own work Original artist: Matthew Clemente • File:Portal-puzzle.svg Source: https://upload.wikimedia.org/wikipedia/en/f/fd/Portal-puzzle.svg License: Public domain Contributors: ? Original artist: ? • File:Question_book-new.svg Source: https://upload.wikimedia.org/wikipedia/en/9/99/Question_book-new.svg License: Cc-by-sa-3.0 Contributors: Created from scratch in Adobe Illustrator. Based on Image:Question book.png created by User:Equazcion Original artist: Tkgd2007 • File:R-DSC08774-WMC.jpg Source: https://upload.wikimedia.org/wikipedia/commons/6/66/R-DSC08774-WMC.jpg License: CC BY-SA 4.0 Contributors: Own work Original artist: JrPol • File:RGBE_filter.svg Source: https://upload.wikimedia.org/wikipedia/commons/c/cb/RGBE_filter.svg License: CC-BY-SA-3.0 Con- tributors: This vector image was created with Inkscape. Original artist: en:User:Cburnett • File:RGBW_Bayer.svg Source: https://upload.wikimedia.org/wikipedia/commons/c/ce/RGBW_Bayer.svg License: Public domain Con- tributors: my own work, modified from another RGBW svg from commons Original artist: Richard F. Lyon • File:RGBW_number_1.svg Source: https://upload.wikimedia.org/wikipedia/commons/0/08/RGBW_number_1.svg License: CC-BY- SA-3.0 Contributors: W3CiThe source code of this SVG is valid. Original artist: en:User:Cburnett • File:RGBW_number_2.svg Source: https://upload.wikimedia.org/wikipedia/commons/c/c4/RGBW_number_2.svg License: CC-BY- SA-3.0 Contributors: W3CiThe source code of this SVG is valid. Original artist: en:User:Cburnett • File:RGBW_number_3.svg Source: https://upload.wikimedia.org/wikipedia/commons/9/95/RGBW_number_3.svg License: CC-BY- SA-3.0 Contributors: W3CiThe source code of this SVG is valid. Original artist: en:User:Cburnett • File:RL_of_PH_Camera_vs_FL.jpg Source: https://upload.wikimedia.org/wikipedia/commons/e/e3/RL_of_PH_Camera_vs_FL.jpg License: CC BY-SA 4.0 Contributors: Own work Original artist: Matt Young • File:Reflex_camera_(description).svg Source: https://upload.wikimedia.org/wikipedia/commons/e/ef/Reflex_camera_%28description% 29.svg License: CC-BY-SA-3.0 Contributors: This vector image was created with Inkscape. Original artist: Anuskafm • File:Reflex_camera_simple_labels.svg Source: https://upload.wikimedia.org/wikipedia/commons/c/c2/Reflex_camera_simple_labels. svg License: CC BY-SA 3.0 Contributors: Own work Original artist: Astrocog • File:Ricoh_GXR_IMG_5351.JPG Source: https://upload.wikimedia.org/wikipedia/commons/6/68/Ricoh_GXR_IMG_5351.JPG Li- cense: CC BY-SA 2.0 fr Contributors: Own work Original artist: Rama • File:Rolleiflex_camera.jpg Source: https://upload.wikimedia.org/wikipedia/commons/a/a0/Rolleiflex_camera.jpg License: CC-BY- SA-3.0 Contributors: Image taken by Juhanson Original artist: Juhanson • File:SDSSFaceplate.gif Source: https://upload.wikimedia.org/wikipedia/en/9/96/SDSSFaceplate.gif License: Fair use Contributors: SDSS Web Site Original artist: Sloan Digital Sky Survey (http://www.sdss.org/) • File:SLR_Pentaprism.svg Source: https://upload.wikimedia.org/wikipedia/commons/6/66/SLR_Pentaprism.svg License: CC BY 3.0 Contributors: ? Original artist: ? • File:SLR_cross_section.svg Source: https://upload.wikimedia.org/wikipedia/commons/a/a0/SLR_cross_section.svg License: CC-BY- SA-3.0 Contributors: Own work with Inkscape based on Image:Slr-cross-section.png Original artist: en:User:Cburnett • File:SONY_ICX024AK_10A_1988_494kpix_CCD.jpg Source: https://upload.wikimedia.org/wikipedia/commons/4/45/SONY_ICX024AK_ 10A_1988_494kpix_CCD.jpg License: CC BY-SA 4.0 Contributors: Own work Original artist: Andrzej w k 2 206 CHAPTER 11. TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• File:Samsung_NX10.jpg Source: https://upload.wikimedia.org/wikipedia/commons/3/31/Samsung_NX10.jpg License: GFDL Con- tributors: http://ko.wikipedia.org/wiki/%ED%8C%8C%EC%9D%BC:Samsung_NX10_x.jpg Original artist: Xenix • File:SensorSizes.svg Source: https://upload.wikimedia.org/wikipedia/commons/9/95/SensorSizes.svg License: Public domain Contrib- utors: Image:SensorSizes.png Original artist: Hotshot977. Subsequently reworked extensively by User:Moxfyre for correct, exact sensor size dimensions and accurate captions. • File:Sensor_sizes_overlaid_inside.svg Source: https://upload.wikimedia.org/wikipedia/commons/f/f0/Sensor_sizes_overlaid_inside. svg License: CC BY-SA 3.0 Contributors: • Sensor_sizes_overlaid.svg Original artist: Sensor_sizes_overlaid.svg: Moxfyre • File:Sharan_Rolleiflex_1.JPG Source: https://upload.wikimedia.org/wikipedia/commons/d/d4/Sharan_Rolleiflex_1.JPG License: CC BY-SA 4.0 Contributors: Own work Original artist: Gisling • File:Sheiner_Viewing_Sunspots_1625.jpg Source: https://upload.wikimedia.org/wikipedia/commons/e/e4/Sheiner_Viewing_Sunspots_ 1625.jpg License: Public domain Contributors: GC6.Sch256.630r, Houghton Library, Harvard University Original artist: Christoph Scheiner (1575-1650), author of book; artist/engraver unidentified. • File:Shutter_priority_mode.svg Source: https://upload.wikimedia.org/wikipedia/commons/c/c6/Shutter_priority_mode.svg License: CC BY-SA 2.5 Contributors: File:ModeDial.svg Original artist: Graphic by : Althepal

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