Glossary
720p/1080i/1080p High-definition video recording standards that refer to the vertical resolution, or the number of horizontal lines on the screen — either 720 or 1080 lines. Seven hundred twenty horizontal lines translate to a width of 1280 pixels, and 1080 lines translate to a width of 1920 pixels. The p stands for progressive scan, which displays the video frame all at once. The i stands for interlaced, an analog compression scheme that allows 60 frames per second (fps) to be transmitted in the same bandwidth as 30 fps by displaying 50 percent of the video frame at a time.
Adobe RGB A color space that encompasses most of the gamut of colors achievable on commercial printers, or approximately 50 percent of the visible colors specified by the International Commission on Illumination (CIE).
AE See automatic exposure (AE).
angle of view The amount of area covered by a lens or viewfinder, measured in degrees. Shorter or wide-angle lenses and zoom settings have a wider angle of view. Longer or telephoto lenses and zoom settings have a narrower angle of view.
aperture The lens opening through which light passes. The mechanism is an iris diaphragm of several blades that can be continuously adjusted to vary the diameter of the opening. Aperture is expressed in f-numbers such as f/8 and f/5.6.
artifact An unintentional or unwanted element in an image caused by an imaging device, or resulting as a byproduct of image processing, such as compression.
artificial light The light from an electric light or flash unit.
Autofocus (AF) A function in which the camera focuses on the subject using the selected AF point or points. Pressing the shutter button halfway sets the focus using the selected AF point.
automatic exposure (AE) A function in which the camera sets all or some of the exposure elements automatically. In automatic shooting modes, the camera sets all exposure settings. In semiautomatic modes, the photographer sets the ISO and either the Aperture-priority AE (Av) mode or the Shutter-priority AE (Tv) mode, and the camera automatically sets the shutter speed or aperture, respectively.
Automatic Exposure (AE) Lock A camera control that enables the photographer to lock the exposure at a point in the scene and focus at a different point in the scene.
available light The natural or artificial light within a scene. This is also called ambient light.
axial chromatic aberration A lens phenomenon that bends different-colored light rays at different angles, thereby focusing them on different planes, which results in color blur or flare. See also chromatic aberration and chromatic difference of magnification.
barrel distortion A lens aberration that can occur when using wide angle lenses and results in a bowing of straight lines outward from the center of a scene.
Basic Zone exposure modes Automatic exposure modes consisting of Scene Intelligent Auto, Creative Auto, and Special Scene.
bit depth The number of bits used to represent each pixel in an image. Higher bit depths translate to more accurate color representation and more colors available for displaying or printing images. In monochrome images, it defines the number of unique shades of gray that are available.
blocked up A description of shadow areas that lack detail.
blooming Bright edges or halos in digital images around light sources, and bright reflections caused by an oversaturation of image sensor photosites.
bokeh The shape and illumination characteristics of the out-of-focus area in an image.
bounce light Light that is directed toward an object, such as a wall or ceiling, so that it reflects (or bounces) light back onto the subject.
brightness The perception of the light reflected or emitted by a source, or the lightness of an object or image. See also lightness and luminance.
buffer Temporary storage for data in a camera or computer.
Bulb A shutter speed setting that keeps the shutter open as long as the shutter button is fully depressed.
cable release An accessory that connects to the camera and allows you to trip the shutter by using the cable instead of pressing the shutter button.
Canon iMAGE Gateway An online resource exclusively available to owners of qualifying Canon products. The Canon iMAGE Gateway gives members 10GB of free online storage space for images, movies, and albums containing up to 500 images. Members and guests can be invited to view images, movies, and albums, and can upload images from Wi-Fi enabled cameras to the Canon iMAGE Gateway. The Map View feature allows users to view images captured with GPS data on a map. The Canon iMAGE Gateway also functions as a conduit for posting movies and albums to popular social media sites like YouTube, Facebook, and Twitter.
chromatic aberration A lens phenomenon that bends different-colored light rays at different angles, thereby focusing them on different planes. Three types of chromatic aberration exist: Chromatic, Lateral, and Transverse. All lenses are subject to chromatic aberration. However, wide angles lenses generally require more correction than longer focal length lenses because of their more extreme convex surface profile. See also axial chromatic aberration.
Chrominance noise Extraneous, unwanted color artifacts in an image.
color balance The color reproduction fidelity of a digital camera’s image sensor and of the lens. In a digital camera, color balance is achieved by setting the white balance to match the scene’s primary light source or by setting a Custom white balance. You can adjust color balance in RAW conversion programs and in image-editing programs for JPEG images.
color/light temperature A numerical description of the color of light measured in degrees Kelvin. Warm, late-day light has a lower color temperature. Cool, early-day light has a higher temperature. Midday light is often considered to be white light (5500K). Flash units are often calibrated to 5000K.
color space In the spectrum of colors, a subset of colors that is encompassed by a particular space. Different color spaces include more or fewer colors. See also RGB and sRGB.
Complementary metal-oxide semiconductor (CMOS) The type of imaging sensor used in the camera to record images. CMOS sensors are chips that use power more efficiently than other types of recording media.
compression A means of reducing file size. Lossy compression permanently discards information from the original file. Lossless compression does not discard information from the original file and allows you to re-create an exact copy of the original file without any data loss. See also lossless and lossy.
contrast The range of tones from light to dark in an image or scene. Also, the degree of distinction between different bright areas in an image; for example, between dark and light areas.
contrasty A term used to describe a scene or image with great differences in brightness between light and dark areas.
Creative Zone exposure modes Manual and semiautomatic exposure modes consisting of Program AE, Shutter-priority AE, Aperture-priority AE, Manual exposure mode, and Bulb.
crop To trim or discard a portion of an image. You can crop when taking a picture by moving closer to the subject to exclude parts of a scene, by zooming in with a zoom lens, or by using an image-editing program.
Cross-type autofocus sensors When standard-precision vertical-line sensitive and horizontal-line sensitive autofocus sensors are combined in a cross configuration. These sensors detect both vertical and horizontal lines at the same time to achieve focus using f/5.6 or faster lenses.
daylight balance A general term used to describe the color of light at approximately 5500K, such as midday sunlight or an electronic flash. A white balance setting on the camera calibrated to give accurate colors in daylight.
depth of field (DOF) The zone of acceptable sharpness in a photo that extends in front of and behind the plane of sharp focus.
diaphragm Adjustable blades inside the lens that open and close to determine the lens aperture.
diffuser Material (such as fabric or paper) that is placed over the light source to soften the light.
dpi (dots per inch) A measure of printing resolution.
dynamic range The difference between the lightest and darkest values in a scene as measured by f-stops. A camera that can hold detail in both highlight and shadow areas over a broad range of f-stops is said to have a high dynamic range.
exposure The amount of light reaching the image sensor. At a given ISO, exposure is the result of the intensity of light multiplied by the length of time the light strikes the sensor.
exposure meter A general term referring to the built-in light meter that measures the light reflected from the subject back to the camera. EOS cameras use reflective meters. The exposure is shown in the viewfinder and on the LCD screen as a scale, and a check mark appears under the scale to indicate ideal exposure, overexposure, or underexposure.
extender Also known as Teleconverter or Tele-extender, an attachment that fits between the camera body and the lens to increase the focal length of the lens.
extension tube A hollow ring attached between the camera lens mount and the lens that increases distance between the optical center of the lens and the sensor, and decreases minimum focusing distance. These are useful for close-up and Macro photography.
fast A term that refers to film, ISO settings, and photographic paper with high sensitivity to light. It also refers to lenses that offer a wide aperture, such as f/2.8 or f/1.4, and to a short shutter speed. See also slow and speed.
filter A piece of glass or plastic that is usually attached to the front of the lens to alter the color, intensity, or quality of the light. Filters are also used to alter the rendition of tones, reduce haze and glare, and create special effects such as soft focus and star effects.
flare Unwanted light reflecting and scattering inside the lens, causing a loss of contrast sharpness, color saturation and/or artifacts in the image.
flat A term that describes a scene, light, photograph, or negative that displays little variation between dark and light tones. This is the opposite of contrasty.
f-number A number representing the maximum light-gathering ability of a lens, or the aperture setting at which a photo is taken. It is calculated by dividing the focal length (f) of the lens by its diameter (D), or f/D. Wide apertures are designated with small numbers, such as f/2.8. Narrow apertures are designated with large numbers, such as f/22. See also aperture.
focal length The distance from the optical center of the lens to the focal plane when the lens is focused on infinity. The longer the focal length is, the greater the magnification.
focal point The point in an image where rays of light intersect after reflecting from a single point on a subject.
focus The point at which light rays from the lens converge to form a sharp image. This is also the sharpest point in an image.
fps (frames per second) In still shooting, fps refers to the number of frames either in One-shot AF or Continuous drive modes that the camera can capture in 1 second. In video film recording, the digital standard is 30 fps.
frame A term used to indicate a single exposure or image. This also refers to the edges around the image.
f-stop See f-number and aperture.
ghosting A type of flare that causes a clearly defined reflection to appear in the image symmetrically opposite to the light source, creating a ghostlike appearance. Ghosting is caused when the sun or a strong light source is included in the scene, and a complex series of reflections occur on the lens surface.
gigabyte The usual measure of the capacity of digital mass storage devices; a gigabyte is slightly more than 1 billion bytes.
grain See noise.
gray-balanced The property of a color model or color profile where equal values of red, green, and blue correspond to a neutral gray value.
gray card A card that reflects a known percentage of the light that falls on it. Typical gray cards reflect 18 percent of the light. Gray cards are standard for taking accurate exposure-meter readings and for providing a consistent target for color balancing during the color-correction process using an image-editing program.
grayscale A scale that shows the progression from black to white using tones of gray. It also refers to rendering a digital image in black, white, and tones of gray. It is also known as monochrome.
High Definition Video (HDV) Video compression and decompression standard.
Advanced Video Codec High Definition (AVCHD) Video compression and decompression standard. See High Definition Video (HDV).
highlight A term describing a light or bright area in a scene, or the lightest area in a scene.
High-precision vertical-line sensitive autofocus sensors Sensors that detect vertical lines to achieve focus using f/2.8 or faster lenses. When slower aperture lenses are used, these autofocus sensors become unavailable and the camera uses standard-precision autofocus sensors instead.
histogram A graph that shows the distribution of tones or colors in an image.
hue The color of a pixel defined by the measure of degrees on the color wheel, many color systems and controls start at zero for red.
infinity The distance marked on the lens between the imaging sensor or film and the optical center of the lens when the lens is focused on the farthest position on the distance scale of a lens (approximately 50 feet and beyond).
ISO (International Organization for Standardization) A rating that describes how sensitive film or an image sensor is to light. ISO in digital cameras refers to the amplification of the signal at the photosites. ISO is expressed in numbers such as ISO 100. The ISO rating doubles as the sensitivity to light doubles. For example, ISO 200 is twice as sensitive to light as ISO 100.
JPEG (Joint Photographic Experts Group) A lossy file format that compresses data by discarding information from the original file to create small image file sizes. See also lossy.
Kelvin A scale for measuring temperature based around absolute zero. The scale is used in photography to quantify the color temperature of light.
LCD (liquid crystal display) monitor The image screen on digital cameras that displays menus and images during playback and Live View shooting.
LCD panel A panel located on the top of the camera; the LCD panel displays exposure information and changes made to exposure, white balance, drive mode, and other camera functions.
lightness A measure of the amount of light reflected or emitted. See also brightness and luminance.
linear A relationship in which doubling the intensity of light produces double the response, as in digital images. The human eye does not respond to light in a linear fashion. See also nonlinear.
lossless A term that refers to file compression that discards no image data. TIFF is a lossless file format. See also compression, lossy, and TIFF.
lossy A term that refers to compression algorithms that discard image data during the process of compressing image data to a smaller size. The higher the compression rate, the more data that is discarded and the lower the image quality. JPEG is a lossy file format. See also compression, JPEG, and lossless.
luminance The light reflected or produced by an area of the subject in a specific direction, measurable by a reflective light meter. See also brightness and lightness.
megabyte Slightly more than 1 million bytes.
megapixel One million pixels. It is used as a measurement of the capacity of a digital image sensor.
memory card In digital photography, removable media that stores digital images, such as the CompactFlash or Secure Digital card used to store images.
metadata Data about data or, more specifically, information about a file. This information, which is embedded in image files by the camera, includes aperture, shutter speed, ISO, focal length, date of capture, and other technical information. Photographers can add additional metadata in image-editing programs, including a name, address, copyright, and so on.
middle gray A shade of gray that has 18 percent reflectance.
midtone An area of average brightness; a medium-gray tone in a photographic print. A midtone is neither a dark shadow nor a bright highlight.
neutral density filter A filter attached to the lens or light source to reduce the required exposure.
noise Extraneous visible artifacts that degrade digital image quality. In digital images, noise appears as unwanted multicolored flecks and as grain that is similar to grain seen in film. Both types of noise are most visible in high-speed digital images captured at high ISO settings.
nonlinear A relationship where a change in stimulus does not always produce a corresponding change in response. For example, if the light in a room is doubled, the human eye does not perceive the room as being twice as bright. See also linear.
normal lens or zoom setting A lens or zoom setting whose focal length is approximately the same as the diagonal measurement of the film or image sensor used. In a full-frame 35mm format, a 50-60mm lens is considered normal. A normal lens more closely represents the perspective of normal human vision.
open up To switch to a larger f-stop, which increases the size of the diaphragm opening.
overexposure Giving an image sensor more light than is required to make an acceptable exposure. The resulting picture is too light.
panning A technique of moving the camera horizontally to follow a moving subject, which keeps the subject sharp but blurs and/or streaks background details.
photosite The place on the image sensor that captures and stores the brightness value for 1 pixel in the image.
pincushion distortion A lens aberration that causes straight lines to bow inward toward the center of the image. Most often associated with telephoto lenses.
pixel The smallest unit of information in a digital image. Pixels contain tone and color that can be modified. The human eye merges very small pixels so that they appear as continuous tones.
plane of critical focus The most sharply focused part of a scene. This is also referred to as the point or plane of sharpest focus.
polarizing filter A filter that reduces glare from reflective surfaces, such as glass or water at certain angles. These are useful for darkening the sky in a scene, increasing color saturation, and in a pinch, functioning as a neutral density filter.
ppi (pixels per inch) The number of pixels per linear inch on a monitor or image file that are used to describe overall display quality or resolution. See also resolution.
RAW A proprietary image file in which the image has little or no in-camera processing. Because image data has not been processed, you can change key camera settings, including brightness and white balance, in a conversion program (such as Canon Digital Photo Professional, Adobe Camera Raw, or Adobe Lightroom) after the picture is taken.
reflective light meter A device — usually a built-in camera meter — that measures light emitted by a photographic subject back to the camera.
reflector A surface used to redirect light into shadow areas of a scene or subject.
resolution The number of pixels in a linear inch. Resolution is the amount of data used to represent detail in a digital image. Also, the resolution of a lens indicates its resolving power when rendering details. Lens resolution is expressed as a numerical value such as 50 or 100 lines, which indicates the number of lines per millimeter of the smallest black-and-white line pattern that can be clearly recorded. The resolution of a printed photograph depends on the resolution of the lens, the image sensor, and the printer. See also ppi.
RGB (Red, Green, Blue) A color model based on additive primary colors of red, green, and blue. This model is used to represent colors based on how much of red, green, and blue is required to produce a given color. See also color space and sRGB.
saturation As it pertains to color, a strong, pure hue undiluted by the presence of white, black, or other colors. The higher the color purity is, the more vibrant the color.
sharp The point in an image at which fine detail is clear and well defined.
shutter A mechanism that regulates the amount of time during which light is allowed into the camera to make an exposure. Shutter time or shutter speed is expressed in seconds and fractions of seconds, such as 1/30 second.
slave A flash unit that is synchronized to and controlled by another flash unit.
slow A reference to film, digital camera settings, and photographic paper with low sensitivity to light, requiring relatively more light to achieve accurate exposure. This also refers to lenses that have a relatively wide aperture, such as f/3.5 or f/5.6, and to a long shutter speed. See also fast and speed.
speed The relative sensitivity to light of photographic materials such as film, digital camera sensors, and photographic paper. This also refers to the ISO setting, and the ability of a lens to let in more light by opening to a wider aperture. See also fast and slow.
spot meter A device that measures reflected light or brightness from a small portion of a subject.
sRGB A color space that approximates the gamut of colors of the most common computer displays. sRGB encompasses approximately 35 percent of the visible colors specified by the International Commission on Illumination (CIE). See also color space and RGB.
Standard-precision vertical-line sensitive and horizontal-line sensitive autofocus sensors Sensors that detect vertical and horizontal lines, respectively, to achieve focus using f/5.6 or faster lenses.
stop See aperture.
stop down To switch to a smaller f-stop, thereby reducing the size of the diaphragm opening.
telephoto A lens or zoom setting with a focal length longer than 50-60mm in full-frame 35mm format.
TIFF (Tagged Image File Format) A universal file format that most operating systems and image-editing applications can read. Commonly used for images, TIFF supports 16.8 million colors and offers lossless compression to preserve all the original file information. See also lossless.
Through-the-Lens (TTL) A system that reads the light passing through a lens that strikes an image sensor.
tonal range The range from the lightest to the darkest tones in an image.
Transverse Chromatic Abberation A lens phenomenon that bends different-colored light rays at different angles, thereby focusing them on different planes; this appears as color fringing, where high-contrast edges show a line of color along their borders. See also axial chromatic aberration and chromatic aberration.
tungsten lighting Common household lighting that uses tungsten filaments. Without filtering or adjusting the correct white balance settings, pictures taken under tungsten light display a yellow-orange colorcast.
underexposure The effect of exposing an image sensor to less light than is required to make an accurate exposure. The resulting picture is too dark.
viewfinder A viewing system that allows the photographer to see all or part of the scene that will be included in the final picture.
vignetting The darkening of edges on an image that can be caused by lens distortion, using a filter, or using a lens hood. It is also used creatively in image editing to draw the viewer’s eye toward the center of the image.
white balance The relative intensity of red, green, and blue in a light source. On a digital camera, white balance compensates for light that is different from daylight to create correct color balance.
wide angle A lens with a focal length shorter than 50-60mm in a full-frame 35mm format.
