Digital Camera Glossary
Dave Bar has worked for Crutchfield since 1981. After a brief 23 year stint in the sales department, he now writes about home audio gear and camera equipment for Crutchfield's catalog and website. Dave has been hooked on electronics ever since putting together a 5-tube AM radio in his high school shop class, and still enjoys tinkering with stereos in his spare time. His interests include gardening, cooking, fishing, photography, and music.
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16:9 widescreen photo mode
Many digital cameras offer this mode to let you take photos that have the same shape as a 16:9 aspect ratio widescreen TV. This size is ideal if you plan on showing your pictures on your high-def set, because they'll fill up the TV's entire screen without losing any picture information.
See focal length.
Video or audio/video outputs are found on most digital cameras; they let you send an image to a TV for easier viewing. An A/V output will also let you send sound (if your camera has that capability, and you recorded a sound clip), while a video output only sends images. Some newer cameras also offer HDMI connectivity for displaying high-res images and videos on a compatible HDTV.
A small metal fitting on the top of a camera that lets you add optional accessories, like an external flash, wireless transmitter, or external microphone. Accessory shoes that can also supply power are sometimes referred to as a hot shoe.
A technology found in some digital cameras that alerts you if your subject blinks when you take a photo. Some anti-blink modes will also capture two images, and only save the photo with less squinting.
A camera's aperture works like the iris of your eye, expanding and contracting to adjust the amount of light which passes through the lens. Aperture is measured in "f-stops." A higher f-stop number corresponds to a smaller opening, which admits less light. Aperture settings are directly related to exposure, permitting you to control the amount of light that reaches your camera's image sensor. Some cameras offer manual aperture adjustment; others offer an aperture priority mode for changing exposure settings.
Aspherical lens element
This lens element's compact, aspherical shape allows a lens to be smaller and lighter. It also results in photos with crystal clear focus across the entire field of the lens — from one edge to the other.
Automatic scene selector
A feature that identifies the kind of shot you're trying to take — such as a landscape, sports photo, or portrait — and adjusts the camera's exposure, shutter speed, white balance, and other settings to take the best picture possible.
Today's digital cameras use a buffer to temporarily store photos before committing them to a regular memory card. That way you don't have to wait for each image to be stored before taking your next shot, and can shoot more quickly or even use a rapidfire "continuous" or "burst" mode.
See continuous/burst mode.
CCD (charge coupled device)
See image sensor.
If you've ever seen a photo in which faint purple fringes are visible at the edges of an object, you've seen the effects of chromatic aberration, or CA. Most of the time, your camera's lens is able to direct all light waves onto the same focal plane. Sometimes, however, it magnifies a few wavelengths differently, or can't quite get them focused on the same focal plane as the others. The result is a mild mismatch within the image. (This effect is more common with extremely wide-angle shots, and is something that many people don't even notice in everyday shots.)
CMOS (complementary metal oxide semiconductor)
See image sensor.
A popular form of removable media originally developed by SanDisk. CompactFlash cards are used in some digital cameras (especially digital SLRs) and other small portable digital devices. They are available in a range of capacities up to 64GB, or even more. UDMA (Ultra Direct Memory Access) CompactFlash cards offer higher data transfer speeds than standard CF cards when used with UDMA-enabled digital SLR cameras and card readers and the UDMA modes are rated by number from 0-7, with higher numbers meaning faster transfer speeds . This is great for folks who use their camera's movie mode, or need to shoot a lot of photos in quick succession and download them rapidly to their computer.
Continuous autofocus mode
In this mode, a camera continually focuses on the subject or subjects in your field of view. It's ideal for recording action scenes, high-energy kids, or other subjects when you want to snap multiple photos in quick succession.
Continuous mode, often called burst mode, lets you press and hold a camera's shutter button to capture a series of shots in rapid succession. This mode is great for recording action scenes, high-energy kids, and pets. Even if one shot of your daughter scoring the winning goal turns out blurry, you've still got plenty more to choose from. Depending on the camera, you may be able to take three, ten, or even more shots in one continuous burst, then select and keep just the images you like best.
Crop factor (focal length multiplier)
If you own a digital SLR camera, you may have heard of crop factor, or focal length multiplier. Basically, crop factor determines the focal length your lens appears to be when it's mounted to a digital SLR camera.
So why would the equivalent focal length be different from the focal length printed on the lens barrel? Because the lens' focal length is based on the assumption that you're using a traditional 35mm film camera, or a digital camera with a sensor as large as a single frame of 35mm film. However, the image sensor on many DSLRs is smaller than a full frame of 35mm film, and the optical result is a seemingly more telephoto focal length than that printed on the barrel.
To find the effective focal length of a lens mounted to an SLR, you multiply its actual focal length by your cam's crop factor. For example, a 70-300mm lens, x 1.5 crop factor, will seem like a 105-450mm lens on your DSLR. Most digital SLRs have a crop factor of 1.5 or 1.6, but different camera brands and models have slightly different-sized sensors, and that will affect each camera's exact crop factor. Full-frame digital SLRs use image sensors that are the same size as a frame of 35mm film, and therefore have no crop factor.
|A frame of 35mm film captures the entire image area produced by a lens mounted to a film SLR camera.||A digital SLR's sensor records only the center portion of the image from the same lens, effectively cropping it.|
|The resulting image appears closer when seen through the viewfinder, providing more apparent telephoto power.|
Cross-type focus sensor
A type of focusing sensor found in digital SLRs that detects and focuses on a subject along both vertical and horizontal lines. They provide higher-accuracy focusing than more commonly found vertical line sensors. High-end SLRs tend to have cross-type sensors more often than entry level or midrange models.
Depth of field
Depth of field (sometimes abbreviated as DOF) describes the areas to the fore and rear of the main focus point that remain sharp, or in focus. With an extremely shallow depth of field, even areas just in front of or behind that point will be out of focus. With a wide depth of field, much of the photograph may be crisply in focus. That's not to say that wider depth of field is always desirable; for instance, many portrait photographers rely on a fairly shallow depth of field to achieve crisp portraits with a blurred background and foreground. Depth of field is affected by factors such as aperture and focal length, although subject distance and sensor type can come into play as well.
The ability to magnify an optical image digitally, using interpolation. Digital cameras can come with quite high levels of digital zoom, but the image quality suffers noticeably as more digital zoom is applied. (Generally, you'll want to stick to optical zoom to ensure a crisp, detailed photo.)
An indicator of your image sensor's ability to capture highlight detail and shadow detail at the same time (or, sometimes, a way to discuss an individual photograph's ability to show detailed dark areas and detailed bright areas at the same time). Because your sensor's pixels can only collect so much light, it is possible to lose detail at one or the other end of the spectrum. The sensors associated with SLRs frequently boast a better dynamic range for the simple fact that each pixel is physically larger and thus able to collect more light information. Good dynamic range generally gives you photographs with more dimensionality and pop.
Effective pixel count
There are two different ways to think about the pixels on a camera's image sensor. "Actual" pixels is a simple count of every pixel present on the sensor. "Effective" pixels, however, is a count of all the pixels used to record an image and it's almost always a tiny bit lower than the "actual" count, because some pixels on a sensor aren't used to record picture information. Effective pixel count is widely used, because it's a much more accurate way to assess a camera's maximum pixel resolution.
An Exif Print-capable camera is great if you're going to be printing out photos on an Exif Print-compatible photo printer. The camera records information like exposure settings and light metering at the time when a photo was taken, and attaches that information to the picture file. A compatible printer takes note of this info and adjusts its settings accordingly, to permit the most accurate, lifelike photo print possible.
Exposure refers to the amount of light to which the camera's image sensor is exposed. Three factors go into exposure: aperture, shutter speed, and sensitivity. By adjusting these factors, either separately and manually, or by using predefined exposure settings, you can affect the way your digital camera handles photos taken in unusual settings (such as pictures taken of people running, or at twilight). Different digital cameras have greater and lesser levels of control over exposure settings.
A feature that lets you adjust the camera's light metering to allow for shooting conditions. A camera's built-in light meter offers a recommended exposure to help photographers set aperture and shutter speed correctly. However, sometimes shooting conditions mean that your camera's best guess isn't quite right (for example, when your subjects are in front of a bright picture window, and the camera is exposing the surrounding scene correctly but leaving your subjects too dark). With exposure compensation, you can tell the camera to increase or decrease exposure values in steps of either 1/3 or 1/2 of a value. Then, you can either set the exposure yourself, based on that light meter reading, or, if you're in automatic, shutter priority, or aperture priority mode, let the camera set the exposure for you.
Face detection is a technology commonly found in point-and-shoot cameras, as well as most hybrids and SLRs. It recognizes one or more human faces in your frame, and sets focus priority on the people in your shot. Let's say you want a picture of your child peeking between two fence posts. Instead of focusing on the more obvious posts, face detection tells the camera to zero in on the child instead, giving you a clear, precisely focused portrait. Face detection can also trigger the camera to select optimal exposure, white balance, and flash settings to best suit your subject.
Flash exposure compensation
A feature found on digital cameras that lets you adjust the light output of the flash to increase or decrease its intensity. This allows you to lighten or darken a scene to your own preferences, beyond what your camera automatically selects.
Focal length is a measure of the distance (in millimeters) from the optical center of a camera's lens to its focal point, which is located on the image sensor. Because digital cameras' focal lengths are measured differently than traditional film cameras (see crop factor), manufacturers usually give a "35mm equivalent" focal length in their specs. This helps 35mm film photographers get a better idea of just how wide-angle or telephoto a digital camera will be in relation to their film cam. A typical digital camera's 35mm equivalent focal length might be 28-280mm, while its actual focal length measures 4.6-46mm. The reason that a range of numbers is given here (28mm to 280mm) is due to the fact that most digital cameras have a zoom lens, which can change focal lengths. A fixed lens has only one focal length.
A camera lens's focal length can tell you a lot about what kinds of pictures it will be able to take well. With a long focal length, like 280mm, a camera is better able to capture far-off subjects (such a lens is also known as "telephoto"). With a short focal length, like 28mm, a camera can capture the scene immediately before it more completely (this kind of lens is considered "wide-angle").
Focus (auto & manual)
Nearly every digital camera utilizes some kind of autofocus capability, a technology which lets the camera automatically create sharp images of the central subject in the frame as you press the shutter button. Most offer multipoint autofocus, which makes it easier to take tricky shots like off-center portraits. Multipoint autofocus uses several points (often between 3 and 9) to assess a framed shot and set focus. Selectable multipoint autofocus gives the user control over which point is used as the focus point.
More sophisticated cameras may also offer manual focus, either as a set of predetermined focus settings, or as a manual focus ring or lever. Manual focus gives you increased control over the detail and clarity of your photos, especially if you plan on taking non-traditional shots and close-ups.
Full frame image sensor
Some advanced digital SLR cameras feature an image sensor that has the same dimensions as a frame of 35mm film found on traditional film SLRs, which is much larger in physical size than sensors found in most digital cameras. All that extra surface area on these "full frame" sensors has several benefits: superior light gathering, lower noise levels, and better resolution.
See accessory shoe.
A digital camera's image sensing element, or as it's often referred to, its image sensor. The image sensor's job is to convert light to electrical energy, which can then be stored in digital form in the camera's memory. An image sensor's photo-capturing power is measured in pixels, and will usually be seen expressed in megapixels. Sometimes, you may see two slightly different pixel counts listed for the same camera's sensor. These numbers represent effective pixel count and actual pixel count.
The two most commonly found technologies used to capture digital images in today's cameras are CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) image sensors. Although both types have their unique strengths and weaknesses, neither one is inherently superior to the other. You can expect high-quality digital photographs from cameras using either technology.
A feature that reduces the blurring of images that occurs as a result of camera shake when taking hand-held shots, particularly at slow shutter speeds or when using telephoto lenses. Optical image stabilization works by using built-in vibration sensors to steer a special set of optical elements inside the lens that compensate for camera movement. Sensor-shifting stabilization works in much the same way, but instead of moving lens elements, the vibration sensors counteract camera shake by moving the image sensor itself.
Interchangeable Lens Hybrid
Just like SLRs, Interchangeable Lens Hybrid Cameras, also known as electronic viewfinder interchangeable lens cameras, feature large image sensors for beautiful pictures, and they let you swap lenses for different shooting scenarios. But their "mirrorless" designs allow the camera body and lenses to be smaller and more portable.
ISO film speed equivalency
An image coding system that processes picture information captured by a camera's image sensor and compresses it for storage on a memory card. Most digital cameras let you adjust the amount of compression applied to an image — greater compression levels let you store more pictures in the same amount of space, but with reduced image quality. Less compression gives you higher quality pics, but allows you to store fewer of them on a memory card.
Color LCD viewscreens are pretty much the norm on today's digital cameras; they can operate in place of, or in addition to, traditional viewfinders. Most cameras' LCDs measure between 1.8" and 3.5" diagonally, with resolutions of up to a million or more pixels. The higher the LCD's resolution, the clearer your view will be of images and camera menus.
Practically speaking, lag time is the pause between when you push the shutter button to take a picture, and when the camera actually takes the picture. In point-and-shoot cameras, that pause is frequently due to the camera's need to set autofocus before taking the picture. In the early days of digital photography, that lag could take a long time — long enough that a fast-moving subject could have exited the frame entirely by the time the camera actually took the shot.
Today's cameras are much, much faster. Still, lag can still be an occasional issue. With a point-and-shoot, one workaround is to half-depress the shutter button in order to autofocus the camera on your subject in advance; then you just push down the rest of the way when you're ready to make your exposure.
Digital SLRs have little-to-no shutter lag (outside of full auto mode or Live View mode, in which they perform more like a point-and-shoot); their increased responsiveness is one of their main selling points over point-and-shoot models.
Live view mode
In traditional digital SLR cameras of the past, the LCD viewscreen could only be used to play back captured images; you'd still need to look through the viewfinder to compose your pictures. However, most models these days offer a live view mode that allows use of the LCD to both compose and review photos, just as you would with a point-and-shoot camera.
A macro, or close-up, lens is one that lets you focus on subjects that are very close to the lens. A macro lens is perfect for shooting close-ups of flowers, insects, or other small objects. Macro lenses come in a range of focal lengths — anything from 28mm to 200mm and beyond.
Many point-and-shoot digital cameras also offer a "Macro" mode. This mode changes the focus setting to let the camera focus on subjects that are very close to the lens. If a macro mode is important to you, be sure to check how close the Macro mode lets you get — can you shoot objects as close as an inch, or only as close as five inches? The closer you can get, the more impressive such close-ups are.
Digital cameras store the photos they take to some kind of memory. In nearly all cases, this will be some kind of removable media. Many cams also include a small amount of built-in memory — enough to let you capture a few extra shots if your memory card fills up, but not enough for regular everyday shooting.
Originally developed by Sony, Memory Stick is a form of removable media used in digital cameras, digital camcorders, handhelds, printers, and more.
Most point-and-shoot digital cameras, and even a select number of newer digital SLRs, let you record video either as an MPEG movie or a Motion JPEG movie. Some even offer HD resolution. And most also record audio. Although these movie modes cannot replace the high-quality video and versatility you get from a digital camcorder, they can be another fun way to capture faces or events.
In digital cameras, the use of an electronic sensor to capture images introduces small levels of noise into each photograph. Small amounts of noise spring naturally from the presence of electricity in the sensor, but it's also caused by the slight variation in light absorption from pixel to pixel. As a result, noise is most easily spotted when you zoom in on sky, darkness, or some other area where you might expect to see uniformity and instead see graininess or tiny bits of color. Turning up the ISO, or sensitivity, of your sensor increases noise as well. Pixel size also has an effect; physically larger pixels are less prone to noise.
Noise reduction, then, is the application of one or more algorithms to a photo in order to eliminate that noise. With effective noise reduction, you can eliminate much of the noise without losing sharpness. Most cameras have some degree of built-in noise reduction.
Some also offer a long-exposure noise reduction mode, as long-exposure shots can accentuate the problem of noise. Photography enthusiasts, however, may choose to disable their camera's noise reduction in order to use more sophisticated, user-adjustable noise reduction software when processing their images.
The ability to magnify a subject for close-ups, by adjusting the camera's lens assembly (thus the name "optical"). Most current digital cameras include an optical zoom lens of some kind. The amount of zoom commonly varies between 3X and 20X, 3X being less range and 20X being considerably more. Although optical zoom specifications may look low compared to digital zoom specifications, remember that optical zoom is the way to go, since it won't result in image degradation.
PictBridge is an international direct-print standard adopted by most major manufacturers of digital cameras and photo printers. With PictBridge, you can connect a compatible camera to a PictBridge photo printer via a USB cable, for easy direct printing without the use of a computer. The gear doesn't have to be the same brand — it just has to be PictBridge-capable.
Short for "picture element." A digital camera's image sensor consists of millions of pixels, each one building up a tiny charge of electricity in response to the light it "sees." The more pixels an image sensor has, the higher the camera's potential resolution. Also see effective pixel count for more info.
Aperture and shutter speed priority modes are a shortcut to easy exposure adjustment. To set exposure manually, you would need to adjust aperture and shutter speed settings separately. With priority modes, when you adjust aperture, shutter speed is automatically reset appropriately — or vice versa. It's a nice way to get more creative without having to worry about understanding all the details behind these kinds of adjustments.
RAW image format
A mode found on digital SLRs, most hybrids, and a few point-and-shoot models that allows all the digital data captured by a camera's image sensor to be stored without first being processed or adjusted by the camera's image processor. The resulting RAW image files, or "digital negatives," can provide greater picture detail, allowing for advanced editing with specialized software on a computer. You won't need to use RAW files if you usually print photos directly from your camera's memory card, but folks who like to customize their images tend to appreciate the extra flexibility and picture quality that RAW files offer.
A shooting mode found on digital SLRs, most hybrids, and a few point-and-shoot models that allows the camera to capture and store unprocessed, lossless RAW images plus much smaller, compressed JPEG files at the same time. The unprocessed RAW image files can provide greater picture detail for advanced editing with specialized software on a computer. The JPEG files are ready to view or print right from the camera with no further processing required.
All of our digital cameras use some kind of reusable removable memory, such as Memory Sticks, CompactFlash cards, and Secure Digital cards. These memory cards offer varying amounts of storage — the more gigabytes, or GB, of memory, the more images that can be stored. See our Blank Media Glossary for more info.
The number of pixels used to capture an image. Resolution ranges from low (640 x 480) to high (3456 x 2592 and up). High resolution makes for sharper pictures; however, high-resolution photos take up more memory than lower-res photos. Different levels of resolution are appropriate for different purposes; see this chart for a few suggestions.
Most cameras offer what are called "scene modes" — settings that are optimized for the demands of certain kinds of photographic scenes or subjects. Some common examples include an action/sports mode that increases a camera's sensitivity, so it can capture crisp shots of intense action without blurring the subject; or a night scene mode that slows down the camera's shutter speed to capture a darkened scene more accurately, with little or no help from the flash. Find out more about scene modes.
Secure Digital® (SD) card
A Secure Digital (SD) card is an SDMI-compliant flash memory card used in many digital cameras, memory players, and other portable digital devices. Like other SDMI-compliant cards, an SD card uses an extra chip to recognize and comply with the requirements imposed on copyright-protected materials.
You'll also come across SDHC and SDXC cards — they're higher-capacity SD card formats. Now, while any SDHC-compliant camera or electronic devcice will be compatible with standard SD cards, an SD-compatible device may not necessarily work with SDHC or SDXC cards. In fact, if your device is more than five years old, there's a chance it won't be SDHC-compliant. So be sure to check your owner's manual to confirm compatibility before buying an SDHC or SDXC card.
With traditional film cameras, sensitivity, also known as ISO, represents the film's sensitivity to light. A lower ISO number means that the film needs more light to take a picture than film with a higher ISO.
Because digital cameras do not use film, manufacturers have had to create "sensitivity" settings. Most digital cameras use 100 as their standard ISO sensitivity setting, and offer a range of other settings from 200 to 400, or more, to mimic the effects of using film with speeds of 100, 200, 400, etc. These higher settings can be very useful in low-light shooting conditions or when faster shutter speeds are required; however, because they are achieved by amplifying or boosting the image sensor's output, they can result in an increase of visible "noise," giving your pictures a somewhat "grainy" look.
The speed at which a digital camera's shutter exposes the image sensor to light. A shutter speed of 1/60 means that the sensor is exposed to light for 1/60th of a second. Faster shutter speeds are good for "freezing" fast-moving action; slow ones allow you to intentionally blur the movement of your subject to emphasize motion, such as water traveling over a set of falls (these types of shots may require a tripod, since the human hand cannot hold a camera steady for very long). Simple digital cameras may have very little shutter speed adjustment; more sophisticated cams often have between 9 and 15 shutter speeds. Many cameras also offer shutter speed priority mode.
Single-lens reflex (SLR)
An SLR, or single-lens reflex, camera is named for its picture-taking mechanism. In a film SLR, the viewfinder uses a 45°-angled mirror to see through the lens; that mirror snaps out of sight quickly when you press the shutter button, to let light enter and expose the film. A digital SLR works the same way, except that the shutter is opening to let an electronic sensor record the image. SLRs are revered by photo enthusiasts because they permit the use of many different specialized lenses and flashes, and provide faster response time and higher continuous shooting speed than most point-and-shoot cameras.
A telephoto lens makes it possible to capture crisp, close-up shots of far-away subjects. The longer the camera's 35mm equivalent focal length, the more telephoto shooting ability the camera has. For example, a 28-300mm equivalent lens has more telephoto power than a wide-angle lens with a 10-24mm equivalent focal length. Often digital camera users refer to optical zoom measurements to indicate a camera's telephoto ability.
USB (Universal Serial Bus) is a "plug and play" interface commonly used on digital cameras, because it allows for quick, easy transfer of digital photos between a camera and a computer or printer. For more information, check out our discussion of USB in the Connections Glossary.
A viewfinder is the small square on the back of a camera that the photographer holds up to his eye. Using the viewfinder is the traditional method of framing photos prior to shooting. Many digital cameras offer an optical viewfinder, just like the ones found on film cameras. A few cameras, most notably those with high-powered telephoto zoom lenses, have electronic viewfinders (EVF) that use a color LCD to show what the lens is seeing, much like a camcorder's viewfinder. A growing number of cameras have given up the viewfinder altogether; framing photos requires you to use the LCD viewscreen. Although a viewfinder doesn't provide as big an image as a viewscreen, it may be preferable when shooting outdoors in direct sunlight, which can wash out the image on a viewscreen. Using a viewfinder can also provide greater freedom from camera shake because the camera is being held against your face for stability while snapping photos.
White balance is the electronic adjustment of light levels to remove unrealistic color tones or hues, so that objects that appear white in person are rendered white in your photos. This process helps recorded images to retain their true colors. All digital cameras offer automatic white balance, and most feature additional preset levels or even custom manual settings. These manual adjustments can provide better color accuracy than the automatic settings when shooting under a mixture of light sources such as incandescent, fluorescent, and daylight.
A wide-angle lens can capture an extra-wide view of the scene immediately before a camera. This allows you to more easily photograph panoramic landscapes for example, or take big group shots without forcing everyone to squeeze together. The shorter (or lower) a lens's 35mm equivalent focal length, the more wide-angle shooting ability the camera has. For example, a 10-24mm equivalent lens has more wide-angle capture ability than a telephoto-oriented 28-300mm equivalent lens.