Animation Descriptions and Links
The animations and extensions listed in this section illustrate the concepts of digital photography. They are accessible from links embedded throughout the Web site and in eBooks published by ShortCourses.com and PhotoCourse.com.
The Camera, Pixels and Images
- Copyright Booklet, straight from the US Copyright Office, introduces
you to a photographer's rights and responsibilities in this important area.
- Cameras are dark boxes animation shows light reflecting off the subject entering the lens that focuses it (upside down) on the ground glass of a camera obscura or view camera, on the film in a film camera, or on the image sensor in a digital camera. Wista camera photos courtesy of HP Marketing Corp http://www.hpmarketingcorp.com).
- Dots on an Inkjet Print animation zooms in on a part of an inkjet print to show you increasing levels of detail. Courtesy of Trevor Anderson.
- Manual for DC 40 is a PDF copy of the original manual that came with this historic digital camera. See what features it had and which it didn't.
- Camera Icons is a printable PDF poster illustrating many of the icons used to identify controls on digital cameras.
- The Light Path Through an SLR shows how light coming through an SLR's lens bounces off a mirror, up into a prism, and out through the viewfinder eyepiece so you can compose a picture through the lens. When you then press the shutter button you'll see how the mirror rises and the shutter opens to expose the image sensor. Illustration courtesy of Nikon Imaging at www.nikon.com.
- Parallax in an Optical Viewfinder demonstrates how your view through a camera's optical viewfinder is different than the view the CCD has through the lens unless the camera is an SLR or it has an electronic viewfinder. The differences between the two views are most noticeable when photographing close-ups. You are actually shooting from a slightly different angle than you see and including or excluding areas at the edge of the frame.
- Continuous displays links to animations showing some applications of continuous mode.
- Continuous Mode shows a series of four images captured in continuous mode and used to create an animated GIF showing motion.
- Continuous Mode was used by Patryk Rebisz to create this entire 4 minute film "Between You and Me". It's an amazing achievement and illustrates the triumph of imagination and creativity over tools. He found that he could record at five frames per second (as opposed to film's 24) and could only shoot in 12 second segments before the camera's memory buffer was filled. You can see and read more about this film and others Patryk has made on his Web site at http://patrykrebisz.com.
- Understanding Exposure illustrates how the amount of light striking the image sensor determines how light or dark the captured image is. As the sensor gathers more light, the image becomes lighter. There is only one point, or perhaps a narrow range, where it is perfectly exposed.
- Where "Charge-Coupled" Comes From illustrates how the term "charge-coupled" (the CC in CCD) comes from the way the charges are read out a row at a time as if the rows were coupled to one another.
- Pixels and Curves illustrates how as the number of pixels increases, details
become finer. You see this especially clearly in curved and diagonal lines.
- Pixelization illustrates that when you enlarge a digital image on the screen far enough, the pixels become increasingly more obvious. Eventually you can see them as small squares, each with its own distinct color. You get the same effect if you make larger and larger prints from the same image.
- Output Devices Determine Image Sizes shows three images 1024 x 768, 800 x 600, and 640 x 480 displayed on a 640 x 480 screen. Only the 640 x 480 image fits on the screen. The others are too large to be shown in their entirety and a viewer would have to scroll around them.
- The Big Lie humorously spoofs those camera companies that try to confuse you by giving inflated figures for their camera (and scanner) resolutions. They use software to blow the images up and then tell you how many pixels are in the ballooned image rather than the number of photosites on the image sensor. Your only defense against these practices is to check photo forums on the Web and read all advertising claims carefully.
- Resolution—The Original Meaning illustrates the original meaning of resolution referred— to the ability of a camera system to resolve the difference between pairs of black and white lines. Higher resolution systems can resolve smaller pairs of lines.
- Image Sensor Sizes vary widely, with larger ones generally being better because they have less noise. The largest common size is the same as a frame of 35mm film (36mm x 24mm) and is referred to as a full-frame sensor. There are larger sensors but they are used mainly in professional and special purpose cameras.
- ISO and Noise illustrates how as the ISO increases, the image sensor needs less light for exposures, but noise increases. Noise appears as random color pixels that make areas of the image discolored and grainy.
- Noise, Example from Cadillac Ranch is a large and very noisy JPEG image straight from the camera. It was taken just before sunrise at Cadillac Ranch in Amarillo, Texas.
- RGB Color illustrates how digital images are created and displayed on screens using just the three primary colors, red, green, and blue— called RGB. When you drag these three images so they are perfectly aligned, the full color image emerges. Since colors are created by mixing various amounts of each of the three colors, this is often called additive color.
- Dust on Your Image Sensor shows three photos of the sky with the camera moved slightly between shots. The images were then opened in Photoshop and their curves were adjusted to expand the tonal range. Those dark spots you see in the same position on each pictures are caused by dust on the sensor.
- RAW vs JPEG Image Quality. In most cases it's hard to tell the differences between images shot in RAW and JPEG formats. However, the differences become most apparent when an image needs serious adjustment to its tonal range as underexposed images do. Since RAW images have 16 bits per pixel, they give you over 65 thousand levels of gray to adjust while JPEGs use only 8 bits per pixel and hence have only 256 levels of gray per pixel.
- The Effects of Compression illustrates how each time a JPEG image is opened, edited, saved, and closed it is compressed. The effects of this compression build up over time especially in smooth areas of the image.
- Exploring Folders displays links to movies on working with folders.
- Expanding and Collapsing Folders shows how clicking the + sign in front of a folder opens it to display it's contents. Clicking the - sign closes a folder.
- Selecting Folders and Files shows how clicking a folder or subfolder selects it and displays its contents in the pane to the right and its path on the Address bar.
- Creating a New Folder illustrates that when you want to create a new folder you first select the folder in which it nested.
- Changing the View shows how Windows files and folders can be displayed in a variety of ways. Just click the Views drop-down arrow and select the view you want to use.
- Dragging and Dropping Files and Folders shows how you can copy of move files or folders by select them and then dragging and dropping. As you drag the files and folders appear as an outline or ghost image and the destination folder on which you can drop them is highlighted.
- You Have Asset Management is a movie from Extensis explaining how their Portfolio program is used to manage a collection of photos. Although it's from a commercial firm, it does a good job of explaining the basics students need to know.
- Adjusting an Image's Tonal Range shows how a photo-editing program lets you adjust the tonal range of an image to make the blacks darker, the whites lighter, and the midtones lighter or darker.
- Adjusting Hue, Saturation and Lightness is a movie showing how this is done by dragging sliders in a photo-editing program.
- Sharpening an Image illustrates how the Unsharp Mask filter increases contrast along edges and lines to give the appearance of increased sharpness. On this butterfly wing the effect is most pronounced along the black lines.
- Understanding Histograms illustrates how as the exposure increases the photo gets lighter and the pixels in the histogram shift to the right.
- Highlight Warnings, found on many cameras displays a highlight warning when you review your images. Areas of the image that are pure white, without any detail, blink or are outlined in color. Skies are often pure white but the only areas on an image that should always be like this are spectral highlights such as reflections.
- Editing can be used to Improve Images makes the point that many images are improved when you adjust their tonal range, color saturation, and sharpness.
- Editing Can be Used to Change Pictures illustrates how a photoediting program with filters, which you can apply with the click of a button, can dramatically change a straight photo into something else.
- Adjusting Perspective illustrates how shooting up at buildings makes the vertical lines look like they are converging. Using transform commands you can correct this by changing the perspective.
- Changing Color Spaces compares the sRGB color space used by most digital cameras to record images to the larger Adobe RGB color space that lets you capture, display, or print as many colors.
- CMYK Colors illustrates how digital prints are created with the three secondary
colors, cyan, magenta, and yellow-called CMY. When you drag these three images so they are perfectly aligned, the full color image emerges. Since colors are created by absorbing CMY so only RGB is reflected to our eyes, this is often called subtractive color.
- Understanding Exposure (REPEAT) illustrates how the amount of light striking the image sensor determines how light or dark the captured image is. As the sensor gathers more light, the image becomes lighter. There is only one point, or perhaps a narrow range, where it is perfectly exposed.
- Changing Exposure Modes uses example images to illustrate when you would select a specific exposure mode. It uses a Canon camera mode dial as the example.
- Shutter Speed Effect on Exposure illustrates how fast shutter speeds let in less light, and if the aperture doesn't change, as the speed gets slower it lets in more light and the picture gets lighter.
- Shutter Speed Effect on Motion illustrates hot the speed of the subject determines which shutter speeds freeze or blur the action. When trying to freeze action, the faster the subject is moving the faster the shutter speed must be.
- Types of Shutters introduces the different kinds of shutters used in digital cameras.
- How a Leaf Shutter Works shows how a leaf shutter has leaves that move to admit or block the light from the sensor. This shutter, often called an iris shutter, mimics the action of the iris in your eye that opens wider in dim light and closes down in bright light.
- How a Focal Plane Shutter Works at Fast Shutter Speeds illustrates how at fast shutter speeds the focal plane shutter curtains move across the image sensor as a slit "painting" the image as it goes.
- How a Focal Plane Shutter Works at Slow Shutter Speeds
illustrates how at slower shutter speeds there is a point at which the entire image sensor is exposed to light. The first curtain opens completely and only then does the second curtain start to close. The fastest shutter speed at which this happens is called the flash sync speed.
- How an Electronic Shutter Works illustrates how an electronic shutter turns on the image sensor to begin recording the exposure and turns it off to end it. In between those two points the image builds up as light is captured by the sensor. Because these shutters have no moving parts they are less expensive. However, they can also be very precise and accurate in more expensive versions.
- Aperture Settings and Exposure displays links to two animations on apertures.
- The Standard Series of Apertures illustrates that as the aperture gets larger, the f/number gets smaller. For example, f/2 is larger than f/16. In the aperture series f/16, f,11, f/8, f/5.6, f/4, f/2.8 and f/2 each setting lets in twice as much light as the previous aperture and half as much as the next.
- Apertures Effect on Exposure illustrates how smaller apertures let in less light, and if the shutter speed doesn't change, as the aperture gets larger it lets in more light and the picture gets lighter.
- Aperture and Depth of Field illustrates that as the aperture gets larger, the depth of field gets shallower and objects in the foreground and background become softer. Here the camera is focused on the gray building so that's where the plane of critical focus is. As the aperture is opened one stop at a time, the depth of field in front and behind that plane gets shallower and shallower.
- Aperture-Shutter Speed Equivalents shows that there is often more than one aperture-shutter speed combination available that gives the same exposure. As shown here by the pairs connected by the red line as the aperture gets larger to let in more light, the shutter speed gets faster to keep the exposure constant.
- How Your Meter Sees makes the point that the exposure meter in your camera doesn't see the same detail you see. It sees only averages, as if you were looking at the scene through a sheet of frosted glass.
- Exposure Compensation is shown to lighten or darken a picture by increasing (+) or decreasing (-) the exposure.
- Exposure Lock shows how you can lock exposure (and focus) on any part of a scene just by pointing the camera at it and pressing the shutter button halfway down. Without releasing the shutter button, you then compose the image the way you want it, and press the shutter button the rest of the way down to take the photo.
- Autoexposure Bracketing (AEB) is shown to automate exposure compensation by taking 3 or 5 photos while the camera automatically varies the exposure for you.
- Image Stabilization shows three videos side by side to show the effect of image stabilization can have. The movies were shot with the camera on a tripod, then handheld with image stabilization on and off. When off, the scene seems to bounce around the screen. With image stabilization turned on, the scene still moves but does so more slowly and smoothly.
- Increasing ISO.(REPEAT) illustrates how as the ISO increases, the image sensor needs less light for exposures, but noise increases. Noise appears as random color pixels that make areas of the image discolored and grainy.
- Distance and Sharpness uses a video camera to capture the scene from the window of a car as it passes St Louis. Notice how things in the foreground zip by and are blurred while those in the background move by in a stately fashion and are relatively sharp.
- The Shutter and Sharpness (REPEAT) illustrates hot the speed of the subject determines which shutter speeds freeze or blur the action. When trying to freeze action, the faster the subject is moving the faster the shutter speed must be.
- The Plane of Critical Focus shows how a camera is focused plane of critical focus moves up the page a line at a time. As the plane moves, a narrow band of depth of field moves along with it and areas go into and out of focus.
- Focus Areas illustrates how many cameras divide the screen into focus areas. When you press the shutter button halfway down, the area covering the subject nearest to the camera is used to set focus. Indicators tell you which area is being used and when focus is locked.
- Servo AF Focus is shown to keep the subject in focus as it moves toward or away from the camera. Here continuous mode was used to capture a series of images, all of which remain in focus. Had servo focus not been used, only the first image in the series would have been in focus.
- Focus Lock illustrates how you can lock focus on any part of a scene even if it isn't covered by one of the camera's focus areas. Just point the camera at the part of the scene where you want the plane of critical focus to fall, and press the shutter button halfway down to lock focus (and exposure). Without releasing the shutter button, compose the image the way you want it and press the shutter button the rest of the way down to take the photo.
- The Aperture and Depth of Field (REPEAT) illustrates that as the aperture gets larger, the depth of field gets shallower and objects in the foreground and background become softer. Here the camera is focused on the gray building so that's where the plane of critical focus is. As the aperture is opened one stop at a time, the depth of field in front and behind that plane gets shallower and shallower.
- Selective Focus demonstrates how you can shift the plane of critical focus to any part of the scene. When a large aperture is used to reduce depth of field, only the areas immediately around the plane are sharp while those farther away are soft. Here the plane shifts between the flowers in the foreground and the building in the background.
Capturing Light and Color
- The Color of Light is a movie showing how a prism breaks a beam of light into its spectrum of colors. A second prism recombines the spectrum into white light. Movie courtesy of Derek G. Kerslake, artist at aboutcolour.com
- Adjusting White Balance uses a white bloodroot flower photographed against a fallen birch tree using a variety of white balance settings. The effects of the settings range from subtle to dramatic.
- Hard and Soft Light illustrates how as a light source gets larger relative to the subject, its light wraps around the subject, reducing contrast and creating a softer light. As the light gets smaller, it becomes harder and the texture on the surface, and the edges of shadows become more distinct. Photos courtesy of Rick Ashley.
- Focal Length and Angle of View shows how as the focal length of a lens increases, it's angle of view gets smaller. You see this effect most clearly when zooming in with a zoom lens.
- Bending light-Part 1 is a 1950s era educational film on light, camera obscuras, and lenses.
- Bending light-Part 2 is a 1950s era educational film on light, camera obscuras, and lenses.
- Bending light-Part 3 is a 1950s era educational film on light, camera obscuras, and lenses.
- Focal Length Factors illustrates how on some 35mm SLRs the lens forms an image circle large enough for 35mm film. A camera using a fullframe sensor will capture the same area. However, when the camera uses a smaller sensor, as most do, it captures a smaller area of the image circle, effectively increasing the focal length of the lens.
- Image Stabilization (REPEAT) shows three videos side by side to show the effect of image stabilization can have. The movies were shot with the camera on a tripod, then handheld with image stabilization on and off. When off, the scene seems to bounce around the screen. With image stabilization turned on, the scene still moves but does so more slowly and smoothly.
- Types of Zoom displays links to animations on optical and digital zoom.
- Optical Zoom is shown changing the image by adjusting the angle of view of the lens. All of the photosites on the image sensor capture unique pixels from the scene.
- Digital Zoom is shown taking a section of the image captured by the sensor and uses software to expand it to full-size. The artificial pixels that are added contain no information directly from the scene and introduce noise that looks like grain.
- 360-Degree VR Panorama captures a gondola tour in Venice August 2005. Interactive 360 degree VR Photo by Hans Nyberg for VRWay.com. You can see more on Han's work at www.panoramas.dk and www.arounder.com.Credit: Hans Nyberg for VRWay.com.
- Wide-angle Lens Distortion shows how a short focal length lenses distort a subject when used at close range. When the same subject is photographed from farther away with a longer focal length lens there is no distortion.
- Macro Magnifications illustrates how the magnification you get with a macro lens is usually specified as a ratio between the size of the image on the image sensor (not in an enlarged print) and the size of the subject. For example, a ratio of 1:1 means the subject and its image are the same size. A ratio of 5:1 means the image is five times larger than the subject.
- Perspective illustrates how as you move closer to a subject and reduce the focal length of the lens to keep the subject the same size, the background looms larger. This is referred to as perspective.
On-Camera Flash Photography
- The Inverse Square Law illustrates how as the distance from the flash
doubles, the amount of light on a given area falls to one-quarter because the same amount of light has to cover an area four times as large. This is known as the inverse square law.
- Flash Sync shows how a camera's flash sync speed is the fastest shutter speed at which the entire image sensor is exposed to the light. At faster shutter speeds part of the sensor is blocked by the shutter because it is starting to close.
- Red-eye is shown to be caused by light from the flash bouncing off the eye's retina and back out to the camera. The retina's blood vessels give a red cast to the reflected light.
- Fill Flash illustrates how when a scene is back lit, fill flash can lighten the
side of the subject facing the camera.
- Flash Sync Timing explores the differences between first and second curtain sync.
- First Curtain Sync shows how this mode fires the flash as soon as the first curtain completely exposes the image sensor.
- Second Curtain Sync shows how this mode fires the flash just before the second curtain starts to close to cover the image sensor.
- Flash Exposure Compensation illustrates how flash exposure compensation works just like exposure compensation except it controls the exposure of the part of the scene illuminated by the flash.
- High Speed Sync shows how at fast shutter speeds a focal plane shutter is never fully open and forms a slit moving across the image frame. To use flash at these speeds your flash must have what is known as focal plane sync or high speed sync so the flash fires repeatedly as the slit moves, exposing one strip of the image at a time.
- High Speed Stroboscopic Photography uses Bryan Mumford's Time Machine with an optical sensor to repeatedly trigger a digital camera so it caught photos of a series of milk drops. One hundred images were captured and combined into this QuickTime movie. The Time Machine is available at http://www.bmumford.com/photo/camctlr.html.
- External Flash shows how one big advantage of an external flash is the ability it gives you to rotate and tilt the flash head so you can bounce flash off walls and ceilings. This makes the light softer and reduces shadows in the image.Photos courtesy of Tim Connor.
- Hard and Soft Light. (REPEAT) illustrates how as a light source gets larger relative to the subject, its light wraps around the subject, reducing contrast and creating a softer light. As the light gets smaller, it becomes harder and the texture on the surface, and the edges of shadows become more distinct. Photos courtesy of Rick Ashley.
- The Main Light shows how the main light can be positioned to the left, above, or right of the subject. Photos courtesy of Rick Ashley.
- The Fill Light shows how as the fill light moves closer to the subject, the shadows cast by the main light get lighter. As the fill light moves farther away, the shadows become darker. Photos courtesy of Rick Ashley.
- The Background Light shows how the background light can be varied for different effects. Photos courtesy of Rick Ashley.
- The Rim Light shows how a rim light behind the subject and facing toward the camera, illuminates the subject's edges so they help visually separate the subject from the background. Photos courtesy of Rick Ashley.
Displaying & Sharing Photos On-Screen
Displaying & Sharing Printed Photos
- CMYK Colors (REPEAT) illustrates how digital prints are created with the three secondary colors, cyan, magenta, and yellow-called CMY. When you drag these three images so they are perfectly aligned, the full color image emerges. Since colors are created by absorbing CMY so only RGB is reflected to our eyes, this is often called subtractive color.
Beyond the Still Image