The following is a general glossary of photographic terms used in this booklet and common to the photographic industry. For more specific definitions and more detailed information, please see the bibliography.
- Ambient Light
- The natural light present and not influenced by electronic flash coloration.
- Aperture
- An adjustable opening centered on the lens axis. It is part of the lens system that admits light.
- ASA/ISO
- The numerical reference to the speed of the film. Represents the American Standards Association and the International Standards Organization.
- Automatic exposure
- An exposure mode in which the photographer sets the aperture and the camera automatically adjusts the shutter speed for a correct exposure. Often used when depth of field is critical to the composition.
- Automatic exposure control
- Camera systems where a photoelectric cell measures the light reaching the film plane and is linked to the shutter or lens aperture to adjust the exposure automatically.
- Automatic flash
- When the camera is set on full automatic mode, the camera’s built-in flash will go off automatically when necessary.
- Backlighting
- Lighting from behind the subject directed towards the camera position.
- Bitmap
- For digital cameras, images formed from pixels with each pixel a shade of gray or color. Using 24-bit color, each pixel can be set to any one of 16 million colors.
- Bounce flash
- The diffusion of light from a flash unit by directing it towards a reflective surface such as a ceiling or wall. This scatters the light, giving a softer illumination.
- Bracketing
- A method of compensating for uncertainties in exposure by making a series of exposures at different exposure values.
- Camera shake
- The unintentional movement of the camera during exposure. Often caused by hand holding, wind, or an unstable tripod.
- Color balance
- For digital cameras, the overall accuracy in which the camera can match the colors in the photograph with those in the original scene.
- Color temperature
- The temperature to which an inert substance would have to be heated in order for it to glow at a particular color. The scale of color temperature significant for photography ranges from the reddish colors of approximately 2000º K through standard ‘white’ at 5400º K, to the bluish colors above 6000º K.
- Color conversion filter
- Colored filter that alters the color temperature of light.
- Contrast
- The difference in tone between adjacent areas of a photograph.
- Depth of focus
- The distance through which the film plane can be moved and still record an acceptably sharp image.
- Depth of field
- The distance through which the subject may extend and still form an acceptably sharp image, in front of and beyond the plane of critical focus. Depth of field can be increased by stopping the lens down to a smaller aperture.
- Diffusor
- Material, often a fabric, that scatters transmitted light.
- Diopter
- A supplementary lens, shaped like a screw-on filter that allows macro photography with a normal telephoto lens.
- Download
- For digital cameras, the process of transferring a file from another device, like your digital camera, to your computer.
- Emulsion
- Light sensitive substance composed of halides suspended in a gelatin, used for photographic film and paper.
- Exposure
- In photography, the amount of light reaching an emulsion, or the film, being the product of intensity and time. It is controlled in the camera through the interaction between the shutter speed and aperture.
- Exposure Latitude
- The range of tolerance a film will take. The range is from the darkest dark to the whitest white or tonal equivalency.
- Exposure compensation
- The ability to adjust exposure by one or two stops to lighten or darken the image. This is controlled manually by adjusting the aperture or shutter appropriately, or through an exposure compensation button on the camera body.
- Exposure/focus lock
- A button usually found on the body of the camera which gives the photographer the ability to point at one part of the scene and hold the shutter button half-way down to lock in exposure and focus settings, then move the camera to recompose the scene as desired.
- Extension
- A fixed or adjustable tube placed between the lens and the camera body, allowing the lens to focus closer and resulting in higher magnification.
- f -stop
- A numerical designation (shown as f/2, f 2.8, or f4) indicating the size of the aperture (lens opening). The notion of relative aperture which is the ratio of the focal length to the diameter of the aperture. The light-gathering power of lenses is usually described by the widest f -stop they are capable of, and lens aperture rings are normally calibrated in a standard series, each stop differing from its adjacent stop by a factor of 1.4.
- Film speed rating
- The sensitivity of a film to light, measured on a standard scale, normally either ASA or ISO.
- Filter
- Transparent material fitted to a lens which alters the characteristics of light passing through it, most commonly in color.
- Fish-eye lens
- A very wide-angle lens characterized by extreme barrel distortion.
- Flare
- Non-image forming light caused by scattering and reflection, that degrades the quality of an image.
- Flash
- An artificial light source which is either built-in or attached to the camera which provides a bright white light onto your subject.
- Flash, fill
- A less than full power amount of light from the electronic flash which is used to fill shadows even when there is enough light to otherwise take the photograph.
- Focal plane
- The plane at which a lens forms a sharp image.
- Focal length
- The distance between the optical center of a lens and its focal plane.
- Focus
- The point at which light rays are converged by a lens, creating an image which is clear to the viewer.
- GIF
- An image file format designed for display of graphics on the Web.
- Grain
- An individual light-sensitive crystal, normally of silver bromide.
- Graininess
- The subjective impression when viewing a photograph of granularity under normal viewing conditions. The eye cannot resolve individual grains, only overlapping clumps of grain.
- Hot Spots
- Areas of unwanted brightness in the image. These can be considered distracting elements.
- Hot shoe
- A mount on top of the camera to which a flash unit is attached, providing an electrical link to the camera for synchronization of the flash with the camera’s shutter.
- Hyperfocal distance
- The minimum distance at which a lens records a subject sharply when focused at infinity.
- Image sensor
- For digital cameras, this is a computerized device containing a photosite for each pixel in the image. Each photosite records the brightness of the light that strikes it during an exposure.
- Infinity
- The point in the distance beyond which everything is in focus when the lens is focused at its maximum distance.
- JPEG
- A popular digital camera file format that uses lossy compression to reduce file sizes. Developed by the Joint Photographic Experts Group. Used extensively for images transferred through the Internet and featured on web pages.
- Lens shade
- Lens attachment that shades the front element from non-image forming light which causes flare.
- Lens coating
- A thin deposited surface on a lens, used to reduce flare.
- Lens
- A transparent device for converging or diverging rays of light by refraction.
- LiOn
- Technical abbreviation for a Lithium ion battery, found on many modern cameras.
- NiCad
- Technical abbreviation for the nickel cadmium battery found in some modern cameras.
- Megapixel
- An image or image sensor with over one million pixels.
- Mirror Lens
- A lens which uses a pair of circular mirrors to fold the light path, resulting in a high-powered lens of shorter than normal length.
- Monopod
- A single-legged camera support.
- Multiple exposure
- An image made up of two or more images superimposed on the same frame of film in the camera.
- Negative
- Photographic image with reversed tones (and reversed colors if color film), used to make a positive image, normally a print, by projection. Negative film is commonly referred to as print film.
- NiMH
- Technical abbreviation for the nickel metal hydride battery found in many modern cameras which is considered ecologically safe and very efficient.
- Normal lens
- Lens with a focal length equal to the diagonal of the film format. It produces an image which appears to have normal perspective and angle of view.
- Open Up
- To open the aperture or slow the shutter speed to let more light in through the lens.
- Overexposure
- Exposure which exceeds the ‘average’ exposure.
- Panning
- A smooth rotation of the camera so as to keep a moving subject continuously in the frame.
- Photosite
- A small area on the surface of an image sensor that captures the brightness for a single pixel in the image. There is one photosite for every pixel in the image.
- Pixelization
- An effect seen when a digital image is enlarged too much and the pixels become obvious.
- Pixels
- The small picture elements that make up a digital photograph.
- Polarization
- Restriction of the direction of the vibration of light. A polarizing filter helps to eliminate reflections from water and non-metallic surfaces.
- Print Film
- (see Negative)
- Rangefinder
- A camera design with a viewfinder separate from the lens. Lines are usually found within the frame to represent the approximate “view” of the lens.
- Red-eye reduction mode
- An automatic exposure mode which fires a preliminary flash to force the pupil of the eye to shrink before firing the main flash to take the picture.
- Red-eye
- An effect caused by the flash which causes peoples eyes to look red.
- Reflector
- Surface used to reflect light. Usually it softens the light at the same time.
- Resolution
- An indication of the sharpness of images on a printout or the display screen, based on the number and density of the pixels used. The more pixels used in an image, the more detail can be seen and the higher the image’s resolution.
- Sensitivity
- The ability of an emulsion or film to respond to light.
- Shutter-priority mode
- An exposure mode in which the photographer controls the shutter speed and the camera automatically adjusts the aperture for the correct exposure.
- Shutter
- Camera mechanism that controls the period of time that image focusing light is allowed to fall on the film.
- Shutter Speed
- The length of time the shutter is open.
- Silhouette
- A subject in the dark with a light background resulting in a profile or shape definition.
- Single lens reflex
- Camera design that allows the image focused on the film plane to be previewed. A hinged mirror diverts the light path into the viewfinder to simplify framing and focusing. Abbreviated to SLR.
- Spot Metering
- Exposure based on a meter reading of a small spot within the metering range of the viewfinder, often highlighted with a highlighted marker.
- Stop Down
- To close the aperture or make the speed of the shutter faster to let less light in through the lens.
- Stop/Step
- A measurement of light entering the camera, controlled by the speed of the shutter and the opening of the aperture. Shutter speed stops are measured by halves and doubles in seconds and parts of seconds – 1 second then ½, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500 and so on. Aperture openings are based on the size of the opening relative to the largest opening. They are preceded by the f symbol and found in halves and doubles of the quantity of light they allow to pass – f 1, f 1.4, f 2, f 2.8, f 4, f 5.6, f 8…
- Telephoto lens
- Lenses which increase the magnification greater than the human eye sees. They range from moderate focal lengths of 70 – 300mm to long focal lengths of greater than 400mm.
- Through the lens (TTL) meter
- Exposure meter built into the camera that measures the light that passes through the lens.
- Tone
- The particular quality of brightness, deepness, or hue of a color.
- Transparency
- Positive image on a transparent film base, designed to be viewed by transmitted light. Transparency film is commonly referred to as slide film.
- Underexposure
- Exposure which has less light than the “average” exposure.
- Viewfinder
- Optical system used for viewing the subject.
- Wavelength of light
- The distance between peaks in a wave of light. This distance, among other things, determines the color.
- Wide angle lens
- A lens that sees a wider perspective than the human eye generally sees. Topically, wide angle lenses range from extreme wide angles of 7 – 14mm to more moderate wide angles from 24 – 35mm.
- Wide-angle lens
- Lens with an angle of view wider than that considered subjectively normal by the human eye, usually wider than 50mm.
- Zone System
- A method of evaluating exposure, with implications for the photographic approach to a subject, developed by Ansel Adams, Minor White and others. Light measurement is converted to exposure settings by dividing the tonal range into specific numbered zones.
- Zoom lens
- Lens with a continuously variable focal length over a certain range at any given focus and aperture. It is generated by differential movement of the lens elements.