Glossary

Adobe RGB A color space created by Adobe Systems Inc. to more closely match the output of inkjet printing devices. See also color space and sRGB.

ambient light The natural light in the scene, also referred to as available light.

angle of view The amount of the scene in front of the camera that a specific lens sees.

aperture The variable size lens opening in the lens that the light passes through before reaching the sensor in the camera. You can adjust the aperture by changing the f-stop, which controls the diaphragm. Aperture is expressed as an f/number — for example, f/5.6.

aperture priority mode A mode that allows you to set the aperture while the camera sets the shutter speed, also called Av or A.

autofocus A camera mode that automatically adjusts the focus, depending on which focus point you select. The autofocus on most digital cameras is engaged by pressing the shutter release button halfway down.

backlighting A method of lighting where the main light is placed behind the subject. See also silhouette.

bounce light Light that is bounced off a surface before hitting the subject to create a more flattering light source. This is used mainly with a dedicated flash unit that can be aimed at a wall or ceiling.

bracket A method in which multiple exposures of the same scene are taken, some below and some above the recommended exposure value.

buffer The camera’s built-in memory that is used as temporary storage before the image data is written to the memory card.

bulb A shutter speed setting that keeps the shutter open as long as the shutter release button is held down. This allows the shutter to remain open longer than a camera’s built-in time limit, which is usually 30 seconds.

cable release A cable with a button on the end that you can attach to your camera, and which allows you to trigger the shutter release without having to press the shutter release button on the camera.

camera shake The small movements of the camera that can cause blurring, especially when the camera is being handheld. Slower shutter speeds and long focal lengths can contribute to this problem.

CCD Charged Coupled Device. A type of sensor found in some digital cameras.

center-weighted metering A metering mode on a camera’s built-in light meter. With center-weighted metering, the entire scene is metered, but a greater emphasis is placed on the center area.

CMOS Complementary Metal Oxide Semiconductor. A type of image sensor found in some dSLRs. See also dSLR.

color space A description of the range of colors that can be displayed or recorded accurately by the current device. See also Adobe RGB and sRGB.

color temperature A method of measuring the color of light using the Kelvin scale. See also Kelvin.

colored gel filters Colored light modifiers that, when placed between the light source and the subject, change the color of the light hitting the subject. It is also possible to put the colored gel between the subject and the camera which would color the whole scene being recorded by the camera.

compression Reducing image file size when saving the image by either removing information (lossy compression) or writing the information in a form that can be re-created without any quality loss (lossless compression). See also lossless and lossy.

contrast The difference between the highlights and the shadows of a scene.

cool A descriptive term for an image or scene that has a bluish cast.

crop To trim the edges of an image; this is usually done in postproduction.

dedicated flash A flash unit that works with the camera either in the camera’s hot shoe or as an external flash triggered by the camera.

depth of field (DOF) The area of acceptably sharp focus in front of and behind the focus point. A shallow depth of field means that the area in acceptable focus is rather small, while a deep depth of field means that the area in acceptable focus is larger.

diaphragm An adjustable opening in the lens that controls the amount of light reaching the sensor. Opening and closing the diaphragm changes the aperture. See also f-stop.

diffused lighting Light that has been scattered and spread out by being bounced off a wall or ceiling or shot through a semi-opaque material, creating a softer, more even light. Diffused lighting can also take the form of sunlight shining through the clouds.

digital noise See noise.

dSLR A digital Single Lens Reflex camera uses a mechanical mirror to show the scene that is visible through the lens attached to the camera. This allows you to compose the scene exactly as it is going to be captured.

equivalent exposures Images that have the same exposure value but use a different combination of shutter speed, aperture, and ISO settings. See also exposure and exposure value.

equivalent focal length The focal length of lenses attached to cropped sensors needs to be translated from the 35mm standard due to their reduced size. The quick way to determine the equivalent focal length of a lens when attached to a cropped sensor camera is to multiply the focal length by 1.5 or 1.6 depending on the camera.

exposure The amount of light that reaches the camera sensor. See also proper exposure.

exposure compensation A method of adjusting the exposure so it differs from the metered reading.

exposure metering Using the light meter built into the camera to determine the proper exposure. See also metering modes.

exposure value A numerical value describing the exposure. A value of 0 is for proper exposures, while positive numbers describe an exposure that is overexposed and negative numbers describe an underexposed image. See also proper exposure.

fast A description referring to the maximum aperture of a lens. Lenses with apertures of f/2.8 and higher are considered fast lenses. See also slow.

fill flash A method where the flash is used to reveal details in shadow areas that would usually be lost.

filter A glass, plastic, or gel piece that goes in front of the lens. Filters can be used to alter the color and intensity of light, add special effects like soft focus, and protect the front elements of the lens.

flash A device that produces a short, bright burst of artificial light. The word flash can be used to describe the unit producing the light or the actual light.

flash exposure compensation An adjustment that changes the amount of light produced by a flash, independent of the exposure settings.

flash sync The method by which the flash is fired at the moment the camera shutter is opened.

flat A description of an image or scene that has very little difference between the light values and the dark values. This also describes an image or scene with low contrast.

focal length The distance from the optical center of the lens when it is focused at infinity to its focal plane (sensor), described in millimeters (mm).

focal plane The area in the camera where the light passing through the lens is focused. In digital cameras, this is the image sensor.

focus The adjustment of the lens to create a distinct and clear image.

front lighting A method of lighting where the main light is placed directly in front of the subject.

f-stop A measure of the opening in the diaphragm that controls the amount of light traveling through the lens. See also diaphragm.

HDR High Dynamic Range photography is a method of combining differently exposed images of the same scene to create a single image with a greater tonal range than a regular photograph.

high contrast A description of an image or scene where the highlights and shadows are at the extreme differences in brightness.

high key A description of a photograph with a light overall tone.

histogram A basic bar graph that shows the number of pixels that fall into each of the shades from pure black to pure white. The histogram view on most digital cameras shows the values of the red, green, and blue color channels as well as the overall tone of the image.

hot shoe The camera mount on top of the camera viewfinder that accepts flash accessories. Each camera manufacturer produces different flash accessories, and those that are made for one brand of camera usually do not work on another camera brand’s body.

interval timer A device that triggers the shutter release at predetermined intervals, allowing for multiple images to be taken automatically over a period of time. These timers are especially useful in time-lapse photography where you need a series of images to be taken over a set length of time.

ISO International Organization for Standardization. An international body that sets standards for film speeds. The standard is also known as ISO 5800:1987 and is a mathematical representation for measuring film speeds. The ISO setting on the dSLR describes the sensitivity to light; the higher the number the more the signal is amplified and the more sensitive to light the sensor appears.

ISO sensitivity A rating that measures the light sensitivity of image sensors in digital cameras, using the standards set for film. Each doubling of the ISO makes the sensor twice as sensitive to light, meaning that for practical purposes, an ISO rating of 200 needs twice as much light as a rating of ISO 400.

JPEG Joint Photographic Experts Group. The most commonly used and universally accepted method for image file compression. JPEG is a lossy form of compression, meaning that information is lost during the compression when the file is saved. JPEG files have a .jpeg or .jpg file extension. See also lossy.

Kelvin (K) A scale used to measure color temperature. The Kelvin scale used in photography is based on the color changes that occur when a theoretical black body is heated to different temperatures. High Kelvin has a blue cast while low Kelvin has a red cast.

LCD Liquid Crystal Display. The type of display used on the back of most digital cameras to preview photos and display menus and shooting data.

light meter A device used to measure the amount of light in a scene. The readings from the light meter can be used to determine what settings produce a proper exposure. All digital cameras have a built-in light meter that reads the intensity of the light being reflected back from whatever is in the scene.

lossless A form of computer file compression applied when saving a file that allows the original data to be reconstructed without losing any of the information. This is useful when you want to ensure that no changes are made to the information. See also compression and TIFF.

lossy A form of computer file compression that reduces the file size by removing data when the image is saved. The file is not an exact match to the original file, but close enough to be of use. This form of compression suffers from generation loss. Repeatedly compressing the same file results in progressive data loss and image degradation. See also compression and JPEG.

low key A description of a photograph with a dark overall tone.

manual exposure mode A camera mode where the photographer determines the exposure by setting both the shutter speed and the aperture.

metering modes The method the camera uses to determine what light to use in the metering process. See also center-weighted metering, scene metering, and spot metering.

middle gray A tone that represents 18 percent reflectance in visible light. All reflective light meters, including the one in your camera, are calibrated to give an average reading of 18 percent gray.

monopod A device with a single leg that helps to steady a camera.

noise Extra unwanted pixels of random color in places where only smooth color should be. Noise is created when the signal from the image sensor is amplified to get those high ISO settings. The higher the ISO in a digital camera, the more noise is created.

noise reduction Software or hardware used to reduce unwanted noise in digital images. See also noise.

normal lens A lens that produces images in a perspective close to that of the human eye.

overexposure A condition that allows more than the recommended amount of light to reach the sensor, causing the image to appear too light and with less detail in the highlights.

panning A method that involves moving the camera in the same direction and speed that the subject is moving, resulting in an image where the subject is in acceptable focus while the background is blurred.

prime lens A lens with a single focal length, which is incapable of zooming to different lengths.

program auto mode A mode in which the camera sets the shutter speed and aperture to achieve the correct exposure. You can adjust these settings to give you a higher level of control over the exposure.

proper exposure Using a combination of shutter speed, aperture, and ISO that allows enough light to reach a sensor so that the image recorded is not too bright or too dark.

RAW A file type that stores the image data without any in-camera processing. Every camera manufacturer has a different RAW file format. RAW files need to be processed before they can be used.

rear-curtain sync The ability to fire the flash at the end of the exposure instead of at the beginning. This freezes the action at the end of the exposure.

red eye A condition that occurs when photographing people with a flash that is too close to the lens (the built-in flash). The light is reflected from the person’s retina (which is covered with tiny blood vessels, thus the red) back toward the camera’s lens.

red-eye reduction A flash mode that fires a short burst of light right before the photograph is taken, in hopes of causing the subject’s pupils to contract, lessening the amount of light that can be reflected back.

reflector Any surface that can be used to redirect light. Specialty reflectors for photography come in different sizes, shapes, and colors and are designed to reflect light onto the subject.

scene metering A metering mode that takes the whole scene into account. Each camera manufacturer has a different method for metering. Check your manual for the method used in your camera. See also center-weighted metering, metering modes, and spot metering.

self-timer A camera feature that allows it to take an exposure after a predetermined amount of time when you have pressed the shutter release button.

sharp A term to describe a well-focused image.

shutter A movable cover that controls the amount of light that is allowed to reach the camera sensor, by opening for a specific length of time designated by the shutter speed.

shutter release button The button that is used to move the shutter out of the way so a photograph can be taken.

shutter speed The amount of time that the shutter is open and letting light reach the image sensor in a camera.

shutter speed priority mode A mode where the photographer sets the shutter speed and the camera sets the aperture.

side lighting A method of lighting where the main light source is to the side of the subject.

silhouette An image or scene where the subject appears as a solid black object against a lighter background. See also backlighting.

slow A description referring to the maximum aperture of a lens. Lenses with a maximum aperture of f/8 are considered very slow. See also fast.

spot metering A metering mode where the only area that the camera uses to meter the light is a small area in the center of the scene.

sRGB A color space created by Hewlett Packard and Microsoft to more closely match display devices. See also Adobe RGB and color space.

stop A term of measurement in photography that refers to any adjustment in the exposure. When stop is used to describe shutter speed, a one-stop increase doubles the shutter speed, and a one-stop decrease halves the shutter speed. When stop is used to describe aperture, a one-stop increase doubles the amount of light reaching the sensor, and a one-stop decrease halves the light reaching the sensor.

telephoto lens A lens with a focal length longer than that of a normal lens.

TIFF Tagged Image File Format. A lossless file format for images that is universally acceptable by image-editing software. See also lossless.

tonal range The shades of gray that exist between solid black and solid white.

top lighting A method of lighting where the main light is placed above the subject.

tripod A device with three legs that is used to hold a camera steady.

tungsten light A light source that produces light with a color temperature of approximately 3200K. See also Kelvin.

underexposure A condition that allows less than the recommended amount of light to reach the sensor, causing the image to appear too dark and a loss of detail in the shadows.

variable-aperture lens A lens that changes the maximum aperture, depending on the focal length.

warm A descriptive term for an image or scene that has an orange or red cast.

white balance An adjustment to the colors that the camera records to match the lighting of the scene.

wide-angle lens A lens description that refers to lenses with shorter-than-normal focal lengths.

zoom lens A lens that has a range of focal lengths.