Camera from Wikipedia, the Free Encyclopedia for Other Uses, See Camera (Disambiguation)
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Camera From Wikipedia, the free encyclopedia For other uses, see Camera (disambiguation). Canon EOS 5D Mark III, a digital single-lens reflex camera A camera is an optical instrument for recording images, which may be stored locally, transmitted to another location, or both. The images may be individual still photographs or sequences of images constituting videos or movies. The word cameracomes 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. Contents [hide] 1 Functional description 2 History 3 Mechanics o 3.1 Image capture o 3.2 Lens o 3.3 Focus o 3.4 Exposure control o 3.5 Shutters . 3.5.1 Complexities 4 Formats 5 Camera accessories 6 Camera designs o 6.1 Plate camera o 6.2 Folding camera o 6.3 Box camera o 6.4 Rangefinder camera o 6.5 Instant picture camera o 6.6 Single-lens reflex o 6.7 Twin-lens reflex o 6.8 Large-format camera o 6.9 Medium-format camera o 6.10 Subminiature camera o 6.11 Movie camera o 6.12 Camcorders o 6.13 Professional video camera o 6.14 Digital camera 7 Image Gallery 8 See also 9 References 10 Bibliography 11 External links Functional description[edit] Basic elements of a modern still camera A camera may work with the light 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 and an image is recorded on a light-sensitive medium. 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 shutter speed.[4][5] A movie camera or a video 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] History[edit] Main article: History of the camera The forerunner to the photographic camera was the camera obscura.[7] In the fifth century B.C., the Chinese philosopher Mo Ti noted that a pinhole can form an inverted and focused image, when light passes through the hole and into a dark area.[8] Mo Ti is the first recorded person to have exploited this phenomenon to trace the inverted image to create a picture.[9] Writing in the fourth century B.C., Aristotle also mentioned this principle.[10] He described observing a partial solar eclipse in 330 B.C. by seeing the image of the Sun projected through the small spaces between the leaves of a tree.[11] In the tenth century, the Arabic scholar Ibn al-Haytham (Alhazen) also wrote about observing a solar eclipse through a pinhole,[12] and he described how a sharper image could be produced by making the opening of the pinhole smaller.[11] English philosopher Roger Bacon wrote about these optical principles in his 1267 treatise Perspectiva.[11] By the fifteenth century, artists and scientists were using this phenomenon to make observations. Originally, an observer had to enter an actual room, in which a pinhole was made on one wall. On the opposite wall, the observer would view the inverted image of the outside.[13] The namecamera obscura, Latin for "dark room", derives from this early implementation of the optical phenomenon.[14] The term was first coined by mathematician and astronomerJohannes Kepler in his Ad Vitellionem paralipomena of 1604.[15] The Italian scientist Giambattista della Porta described the camera obscura in detail in his 1558 work Magia Naturalis, and specifically suggested that an artist could project a camera obscura's images onto paper, and trace the outlines.[16] The camera obscura was popular as an aid for drawing and painting from the 1600s to the 1800s.[17] Portable set-ups were devised in the 17th century. For example, Kepler had built a portable tent, and outfitted the camera obscura with a lens by 1620.[18] [19] This set-up remained popular up to the early 1800s.[20] 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.[21] 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.[22] 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.[23]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 influenced by heat or exposure to air.[24] 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 ammonia solution.[24] The first person to use this chemistry to create images was Thomas Wedgwood.[23] 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.[25] Camera obscura. Light enters a dark box through a small hole and creates an inverted image on the wall opposite the hole.[26] View from the Window at Le Gras (1826), the earliest surviving photograph[27] The Giroux daguerreotype camera, the first to be commercially produced[28] The first permanent photograph of a camera image was made in 1826 by Joseph Nicéphore Niépce using a sliding wooden box camera made by Charles and Vincent Chevalier in Paris. [29] 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.[30] Niépce called his process "heliography".[31] 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.[32] 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.[33] By 1837, he was able to fix 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.[34] In the 1830s, the English scientist Henry Fox Talbot independently invented a process to fix camera images using silver salts.[35] 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 calotypes. The calotyping process was the first to utilize negative prints, which reverse all values in the photograph - black shows up as white and vice versa.[36] Negative prints allow, in principle, unlimited duplicates of the positive print to be made.[37] Calotyping also introduced the ability for a printmaker to alter the resulting image through retouching.[38]Calotypes were never as popular or widespread as daguerreotypes,[39] owing mainly to the fact that the latter produced sharper details.[40] 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. [41] 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 France,[42] with each device and accessories costing 400 francs.[43] The camera was a double-box design, with a landscape lensfitted 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.