The Trade-Off Between Image Resolution and Field of View: the Influence of Lens Selection
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“Digital Single Lens Reflex”
PHOTOGRAPHY GENERIC ELECTIVE SEM-II DSLR stands for “Digital Single Lens Reflex”. In simple language, a DSLR is a digital camera that uses a mirror mechanism to either reflect light from a camera lens to an optical viewfinder (which is an eyepiece on the back of the camera that one looks through to see what they are taking a picture of) or let light fully pass onto the image sensor (which captures the image) by moving the mirror out of the way. Although single lens reflex cameras have been available in various shapes and forms since the 19th century with film as the recording medium, the first commercial digital SLR with an image sensor appeared in 1991. Compared to point-and-shoot and phone cameras, DSLR cameras typically use interchangeable lenses. Take a look at the following image of an SLR cross section (image courtesy of Wikipedia): When you look through a DSLR viewfinder / eyepiece on the back of the camera, whatever you see is passed through the lens attached to the camera, which means that you could be looking at exactly what you are going to capture. Light from the scene you are attempting to capture passes through the lens into a reflex mirror (#2) that sits at a 45 degree angle inside the camera chamber, which then forwards the light vertically to an optical element called a “pentaprism” (#7). The pentaprism then converts the vertical light to horizontal by redirecting the light through two separate mirrors, right into the viewfinder (#8). When you take a picture, the reflex mirror (#2) swings upwards, blocking the vertical pathway and letting the light directly through. -
Estimation and Correction of the Distortion in Forensic Image Due to Rotation of the Photo Camera
Master Thesis Electrical Engineering February 2018 Master Thesis Electrical Engineering with emphasis on Signal Processing February 2018 Estimation and Correction of the Distortion in Forensic Image due to Rotation of the Photo Camera Sathwika Bavikadi Venkata Bharath Botta Department of Applied Signal Processing Blekinge Institute of Technology SE–371 79 Karlskrona, Sweden This thesis is submitted to the Department of Applied Signal Processing at Blekinge Institute of Technology in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering with Emphasis on Signal Processing. Contact Information: Author(s): Sathwika Bavikadi E-mail: [email protected] Venkata Bharath Botta E-mail: [email protected] Supervisor: Irina Gertsovich University Examiner: Dr. Sven Johansson Department of Applied Signal Processing Internet : www.bth.se Blekinge Institute of Technology Phone : +46 455 38 50 00 SE–371 79 Karlskrona, Sweden Fax : +46 455 38 50 57 Abstract Images, unlike text, represent an effective and natural communica- tion media for humans, due to their immediacy and the easy way to understand the image content. Shape recognition and pattern recog- nition are one of the most important tasks in the image processing. Crime scene photographs should always be in focus and there should be always be a ruler be present, this will allow the investigators the ability to resize the image to accurately reconstruct the scene. There- fore, the camera must be on a grounded platform such as tripod. Due to the rotation of the camera around the camera center there exist the distortion in the image which must be minimized. -
Depth of Field Lenses Form Images of Objects a Predictable Distance Away from the Lens. the Distance from the Image to the Lens Is the Image Distance
Depth of Field Lenses form images of objects a predictable distance away from the lens. The distance from the image to the lens is the image distance. Image distance depends on the object distance (distance from object to the lens) and the focal length of the lens. Figure 1 shows how the image distance depends on object distance for lenses with focal lengths of 35 mm and 200 mm. Figure 1: Dependence Of Image Distance Upon Object Distance Cameras use lenses to focus the images of object upon the film or exposure medium. Objects within a photographic Figure 2 scene are usually a varying distance from the lens. Because a lens is capable of precisely focusing objects of a single distance, some objects will be precisely focused while others will be out of focus and even blurred. Skilled photographers strive to maximize the depth of field within their photographs. Depth of field refers to the distance between the nearest and the farthest objects within a photographic scene that are acceptably focused. Figure 2 is an example of a photograph with a shallow depth of field. One variable that affects depth of field is the f-number. The f-number is the ratio of the focal length to the diameter of the aperture. The aperture is the circular opening through which light travels before reaching the lens. Table 1 shows the dependence of the depth of field (DOF) upon the f-number of a digital camera. Table 1: Dependence of Depth of Field Upon f-Number and Camera Lens 35-mm Camera Lens 200-mm Camera Lens f-Number DN (m) DF (m) DOF (m) DN (m) DF (m) DOF (m) 2.8 4.11 6.39 2.29 4.97 5.03 0.06 4.0 3.82 7.23 3.39 4.95 5.05 0.10 5.6 3.48 8.86 5.38 4.94 5.07 0.13 8.0 3.09 13.02 9.93 4.91 5.09 0.18 22.0 1.82 Infinity Infinite 4.775 5.27 0.52 The DN value represents the nearest object distance that is acceptably focused. -
What's a Megapixel Lens and Why Would You Need One?
Theia Technologies white paper Page 1 of 3 What's a Megapixel Lens and Why Would You Need One? It's an exciting time in the security department. You've finally received approval to migrate from your installed analog cameras to new megapixel models and Also translated in Russian: expectations are high. As you get together with your integrator, you start selecting Что такое мегапиксельный the cameras you plan to install, looking forward to getting higher quality, higher объектив и для чего он resolution images and, in many cases, covering the same amount of ground with нужен one camera that, otherwise, would have taken several analog models. You're covering the basics of those megapixel cameras, including the housing and mounting hardware. What about the lens? You've just opened up Pandora's Box. A Lens Is Not a Lens Is Not a Lens The lens needed for an IP/megapixel camera is much different than the lens needed for a traditional analog camera. These higher resolution cameras demand higher quality lenses. For instance, in a megapixel camera, the focal plane spot size of the lens must be comparable or smaller than the pixel size on the sensor (Figures 1 and 2). To do this, more elements, and higher precision elements, are required for megapixel camera lenses which can make them more costly than their analog counterparts. Figure 1 Figure 2 Spot size of a megapixel lens is much smaller, required Spot size of a standard lens won't allow sharp focus on for good focus on megapixel sensors. a megapixel sensor. -
EVERYDAY MAGIC Bokeh
EVERYDAY MAGIC Bokeh “Our goal should be to perceive the extraordinary in the ordinary, and when we get good enough, to live vice versa, in the ordinary extraordinary.” ~ Eric Booth Welcome to Lesson Two of Everyday Magic. In this week’s lesson we are going to dig deep into those magical little orbs of light in a photograph known as bokeh. Pronounced BOH-Kə (or BOH-kay), the word “bokeh” is an English translation of the Japanese word boke, which means “blur” or “haze”. What is Bokeh? bokeh. And it is the camera lens and how it renders the out of focus light in Photographically speaking, bokeh is the background that gives bokeh its defined as the aesthetic quality of the more or less circular appearance. blur produced by the camera lens in the out-of-focus parts of an image. But what makes this unique visual experience seem magical is the fact that we are not able to ‘see’ bokeh with our superior human vision and excellent depth of field. Bokeh is totally a function ‘seeing’ through the lens. Playing with Focal Distance In addition to a shallow depth of field, the bokeh in an image is also determined by 1) the distance between the subject and the background and 2) the distance between the lens and the subject. Depending on how you Bokeh and Depth of Field compose your image, the bokeh can be smooth and ‘creamy’ in appearance or it The key to achieving beautiful bokeh in can be livelier and more energetic. your images is by shooting with a shallow depth of field (DOF) which is the amount of an image which is appears acceptably sharp. -
Using Depth Mapping to Realize Bokeh Effect with a Single Camera Android Device EE368 Project Report Authors (SCPD Students): Jie Gong, Ran Liu, Pradeep Vukkadala
Using Depth Mapping to realize Bokeh effect with a single camera Android device EE368 Project Report Authors (SCPD students): Jie Gong, Ran Liu, Pradeep Vukkadala Abstract- In this paper we seek to produce a bokeh Bokeh effect is usually achieved in high end SLR effect with a single image taken from an Android device cameras using portrait lenses that are relatively large in size by post processing. Depth mapping is the core of Bokeh and have a shallow depth of field. It is extremely difficult effect production. A depth map is an estimate of depth to achieve the same effect (physically) in smart phones at each pixel in the photo which can be used to identify which have miniaturized camera lenses and sensors. portions of the image that are far away and belong to However, the latest iPhone 7 has a portrait mode which can the background and therefore apply a digital blur to the produce Bokeh effect thanks to the dual cameras background. We present algorithms to determine the configuration. To compete with iPhone 7, Google recently defocus map from a single input image. We obtain a also announced that the latest Google Pixel Phone can take sparse defocus map by calculating the ratio of gradients photos with Bokeh effect, which would be achieved by from original image and reblured image. Then, full taking 2 photos at different depths to camera and defocus map is obtained by propagating values from combining then via software. There is a gap that neither of edges to entire image by using nearest neighbor method two biggest players can achieve Bokeh effect only using a and matting Laplacian. -
Depth of Field in Photography
Instructor: N. David King Page 1 DEPTH OF FIELD IN PHOTOGRAPHY Handout for Photography Students N. David King, Instructor WWWHAT IS DDDEPTH OF FFFIELD ??? Photographers generally have to deal with one of two main optical issues for any given photograph: Motion (relative to the film plane) and Depth of Field. This handout is about Depth of Field. But what is it? Depth of Field is a major compositional tool used by photographers to direct attention to specific areas of a print or, at the other extreme, to allow the viewer’s eye to travel in focus over the entire print’s surface, as it appears to do in reality. Here are two example images. Depth of Field Examples Shallow Depth of Field Deep Depth of Field using wide aperture using small aperture and close focal distance and greater focal distance Depth of Field in PhotogPhotography:raphy: Student Handout © N. DavDavidid King 2004, Rev 2010 Instructor: N. David King Page 2 SSSURPRISE !!! The first image (the garden flowers on the left) was shot IIITTT’’’S AAALL AN ILLUSION with a wide aperture and is focused on the flower closest to the viewer. The second image (on the right) was shot with a smaller aperture and is focused on a yellow flower near the rear of that group of flowers. Though it looks as if we are really increasing the area that is in focus from the first image to the second, that apparent increase is actually an optical illusion. In the second image there is still only one plane where the lens is critically focused. -
Aperture Efficiency and Wide Field-Of-View Optical Systems Mark R
Aperture Efficiency and Wide Field-of-View Optical Systems Mark R. Ackermann, Sandia National Laboratories Rex R. Kiziah, USAF Academy John T. McGraw and Peter C. Zimmer, J.T. McGraw & Associates Abstract Wide field-of-view optical systems are currently finding significant use for applications ranging from exoplanet search to space situational awareness. Systems ranging from small camera lenses to the 8.4-meter Large Synoptic Survey Telescope are designed to image large areas of the sky with increased search rate and scientific utility. An interesting issue with wide-field systems is the known compromises in aperture efficiency. They either use only a fraction of the available aperture or have optical elements with diameters larger than the optical aperture of the system. In either case, the complete aperture of the largest optical component is not fully utilized for any given field point within an image. System costs are driven by optical diameter (not aperture), focal length, optical complexity, and field-of-view. It is important to understand the optical design trade space and how cost, performance, and physical characteristics are influenced by various observing requirements. This paper examines the aperture efficiency of refracting and reflecting systems with one, two and three mirrors. Copyright © 2018 Advanced Maui Optical and Space Surveillance Technologies Conference (AMOS) – www.amostech.com Introduction Optical systems exhibit an apparent falloff of image intensity from the center to edge of the image field as seen in Figure 1. This phenomenon, known as vignetting, results when the entrance pupil is viewed from an off-axis point in either object or image space. -
12 Considerations for Thermal Infrared Camera Lens Selection Overview
12 CONSIDERATIONS FOR THERMAL INFRARED CAMERA LENS SELECTION OVERVIEW When developing a solution that requires a thermal imager, or infrared (IR) camera, engineers, procurement agents, and program managers must consider many factors. Application, waveband, minimum resolution, pixel size, protective housing, and ability to scale production are just a few. One element that will impact many of these decisions is the IR camera lens. USE THIS GUIDE AS A REFRESHER ON HOW TO GO ABOUT SELECTING THE OPTIMAL LENS FOR YOUR THERMAL IMAGING SOLUTION. 1 Waveband determines lens materials. 8 The transmission value of an IR camera lens is the level of energy that passes through the lens over the designed waveband. 2 The image size must have a diameter equal to, or larger than, the diagonal of the array. 9 Passive athermalization is most desirable for small systems where size and weight are a factor while active 3 The lens should be mounted to account for the back athermalization makes more sense for larger systems working distance and to create an image at the focal where a motor will weigh and cost less than adding the plane array location. optical elements for passive athermalization. 4 As the Effective Focal Length or EFL increases, the field 10 Proper mounting is critical to ensure that the lens is of view (FOV) narrows. in position for optimal performance. 5 The lower the f-number of a lens, the larger the optics 11 There are three primary phases of production— will be, which means more energy is transferred to engineering, manufacturing, and testing—that can the array. -
AG-AF100 28Mm Wide Lens
Contents 1. What change when you use the different imager size camera? 1. What happens? 2. Focal Length 2. Iris (F Stop) 3. Flange Back Adjustment 2. Why Bokeh occurs? 1. F Stop 2. Circle of confusion diameter limit 3. Airy Disc 4. Bokeh by Diffraction 5. 1/3” lens Response (Example) 6. What does In/Out of Focus mean? 7. Depth of Field 8. How to use Bokeh to shoot impressive pictures. 9. Note for AF100 shooting 3. Crop Factor 1. How to use Crop Factor 2. Foal Length and Depth of Field by Imager Size 3. What is the benefit of large sensor? 4. Appendix 1. Size of Imagers 2. Color Separation Filter 3. Sensitivity Comparison 4. ASA Sensitivity 5. Depth of Field Comparison by Imager Size 6. F Stop to get the same Depth of Field 7. Back Focus and Flange Back (Flange Focal Distance) 8. Distance Error by Flange Back Error 9. View Angle Formula 10. Conceptual Schema – Relationship between Iris and Resolution 11. What’s the difference between Video Camera Lens and Still Camera Lens 12. Depth of Field Formula 1.What changes when you use the different imager size camera? 1. Focal Length changes 58mm + + It becomes 35mm Full Frame Standard Lens (CANON, NIKON, LEICA etc.) AG-AF100 28mm Wide Lens 2. Iris (F Stop) changes *distance to object:2m Depth of Field changes *Iris:F4 2m 0m F4 F2 X X <35mm Still Camera> 0.26m 0.2m 0.4m 0.26m 0.2m F4 <4/3 inch> X 0.9m X F2 0.6m 0.4m 0.26m 0.2m Depth of Field 3. -
A Guide to Smartphone Astrophotography National Aeronautics and Space Administration
National Aeronautics and Space Administration A Guide to Smartphone Astrophotography National Aeronautics and Space Administration A Guide to Smartphone Astrophotography A Guide to Smartphone Astrophotography Dr. Sten Odenwald NASA Space Science Education Consortium Goddard Space Flight Center Greenbelt, Maryland Cover designs and editing by Abbey Interrante Cover illustrations Front: Aurora (Elizabeth Macdonald), moon (Spencer Collins), star trails (Donald Noor), Orion nebula (Christian Harris), solar eclipse (Christopher Jones), Milky Way (Shun-Chia Yang), satellite streaks (Stanislav Kaniansky),sunspot (Michael Seeboerger-Weichselbaum),sun dogs (Billy Heather). Back: Milky Way (Gabriel Clark) Two front cover designs are provided with this book. To conserve toner, begin document printing with the second cover. This product is supported by NASA under cooperative agreement number NNH15ZDA004C. [1] Table of Contents Introduction.................................................................................................................................................... 5 How to use this book ..................................................................................................................................... 9 1.0 Light Pollution ....................................................................................................................................... 12 2.0 Cameras ................................................................................................................................................ -
Calumet's Digital Guide to View Camera Movements
Calumet’sCalumet’s DigitalDigital GuideGuide ToTo ViewView CameraCamera MovementsMovements Copyright 2002 by Calumet Photographic Duplication is prohibited under law Calumet Photographic Chicago IL. Copies may be obtained by contacting Richard Newman @ [email protected] What you can expect to find inside 9 Types of view cameras 9 Necessary accessories 9 An overview of view camera lens requirements 9 Basic view camera movements 9 The Scheimpflug Rule 9 View camera movements demonstrated 9 Creative options There are two Basic types of View Cameras • Standard “Rail” type view camera advantages: 9 Maximum flexibility for final image control 9 Largest selection of accessories • Field or press camera advantages: 9 Portability while maintaining final image control 9 Weight Useful and necessary Accessories 9 An off camera meter, either an ambient or spot meter. 9 A loupe to focus the image on the ground glass. 9 A cable release to activate the shutter on the lens. 9 Film holders for traditional 4x5 film holder image capture. 9 A Polaroid back for traditional test exposures, to check focus or final art. VIEW CAMERA LENSES ARE DIVIDED INTO THREE GROUPS, WIDE ANGLE, NORMAL AND TELEPHOTO WIDE ANGLES LENSES WOULD BE FROM 38MM-120MM FOCAL LENGTHS FROM 135-240 WOULD BE CONSIDERED NORMAL TELEPHOTOS COULD RANGE FROM 270MM-720MM FOR PRACTICAL PURPOSES THE FOCAL LENGTHS DISCUSSED ARE FOR 4X5” FORMAT Image circle- The black lines are the lens with no tilt and the red lines show the change in lens coverage with the lens tilted. If you look at the film plane, you can see that the tilted lens does not cover the film plane, the image circle of the lens is too small with a tilt applied to the camera.