Photo Glossary

Angle of view. The amount of a scene that can be recorded by a particular lens; determined by the focal length of the lens.

Aperture. The lens opening formed by the iris diaphragm inside the lens. The size is variable and is adjusted by the aperture control.

Aperture control. The ring on the camera lens (a pushbutton on some models) that, when turned, adjusts the size of the opening in the iris diaphragm and changes the amount of light that reaches the film.

Aperture-priority mode. An automatic exposure system in which the photographer sets the aperture (f-stop) and the camera selects a shutter speed for normal exposure.

APS. Advanced Photo System. A film technology recently developed by Kodak that facilitates film loading. Users also get a card that shows all the frames, plus other advantages. Film size is smaller than 35mm.

Available light. A general term implying relatively dim light that already exists where a photograph is to be made.

Averaging meter. An exposure meter with a wide angle of view. The indicated exposure is based on an average of all the light values in the scene.

Body. The light-tight box that contains the camera mechanisms and protects the film from light until you are ready to make an exposure.

Bracketing. Taking several photographs of the same scene at different exposure settings, some greater than and some less than the setting indicated by the meter, to ensure a well-exposed photograph.

Center-weighted meter. A through-the-lens exposure meter that measures light values from the entire scene but gives greater emphasis to those in the center of the image area.

Close-up lens. An attachment placed in front of an ordinary lens to allow focusing at a shorter distance in order to increase image size.

Color balance. The overall accuracy with which the colors in a color photograph match or are capable of matching those in the original scene. Color films are balanced for use with specific light sources.

Color saturation. Intensity of color in a photograph. To increase color saturation when shooting transparencies, under-expose slightly, perhaps by 1/3 of an f-stop.

Color temperature. Description of the color of a light source. Measured on a scale of degrees Kelvin.

Contrast. The difference between the light and dark parts of a scene or photograph.

Crop. To trim the edges of an image, often to improve the composition. Cropping can be done by moving the camera position while viewing a scene, or by trimming the finished print.

Daylight film. Color film that has been balanced to produce natural-looking color when exposed in daylight.

Depth of field. The distance between the nearest and farthest points that appear in acceptably sharp focus in a photograph. Depth of field varies with lens aperture, focal length and camera-to-subject distance.

Diaphragm (iris diaphragm). The mechanism controlling the size of the lens opening and therefore the amount of light that reaches the film. It consists of several overlapping metal leaves inside the lens that form a circular opening of variable sizes. (You can see it as you look into the front of the lens.) The size of the opening is referred to as the f-stop or aperture.

Diffused light. Light that has been scattered by reflection or by passing through a translucent material. An even, often shadowless light.

Digital camera. Instead of using film,this kind of camera records data in "pixels," small squares of light of varying hues that can be directly loaded into and interpreted by a computer.

Direct light. Light shining directly on the subject and producing strong highlights and deep shadows.

Electronic flash (strobe). A camera accessory that provides a brief but powerful flash of light. A battery-powered unit requires occasional recharging or battery replacement.

Environmental portrait. A photograph in which the subject's surroundings are important to the portrait.

Exposure. 1. The act of allowing light to strike a light-sensitive surface. 2. The amount of light reaching the film, controlled by the combination of aperture and shutter speed.

Exposure meter (light meter). An instrument that measures the amount of light and provides aperture and shutter speed combinations for correct exposures. Exposure meters may be built into the camera or they may be separate instruments.

Exposure mode. The type of camera operation (such as manual, shutter-priority, aperture-priority) that determines which controls you set and which ones the camera sets automatically. Some cameras operate only in one mode. Others may be used in a variety of modes.

Extension tubes. Metal rings attached between the camera lens and the body to allow closer-than-normal focusing in order to increase the image size.

Fast. Describes 1. a film that is very sensitive to light; 2. a lens that opens to a very wide aperture; 3. a short shutter speed.

Film. A roll or sheet of a flexible material coated on one side with a light-sensitive emulsion and used in the camera to record an image.

Film advance lever. A device, usually on top of the camera, that winds the film forward a measured distance so that an unexposed segments moves into place behind the shutter.

Film speed. The relative sensitivity to light of photographic film. Measured by ISO (or ASA or DIN) rating. Faster film (higher number) is more sensitive to light and requires less exposure than slower film. See also Speed.

Filter. 1. A piece of colored glass or plastic placed in front of the camera lens to alter the quality of light reaching the film. 2. To use such a filter.

Flare. Non--image-forming light that reaches the film, resulting in a loss of contrast or an overall grayness in the final image. Caused by stray light reflecting between the surfaces of the lens.

Flash. 1. A short burst of light emitted by a flashbulb or electronic flash unit at the same time the film is exposed. 2. The equipment used to produce this light.

Focal length. The distance from an internal part of a lens (the rear nodal plane) to the film plane when the lens is focused on infinity. The focal length is usually expressed in millimeters (mm) and determines the angle of view (how much of the scene can be included in the picture) and the size of objects in the image. A 100mm lens, for example, has a narrower angle of view and magnifies objects more than a lens of shorter focal length.

Focal plane. The surface inside the camera on which a focused lens forms a sharp image.

Focal-plane shutter. A camera mechanism that admits light to expose film by opening a slit just in front of the film (focal) plane.

Focus. 1. The point at which the rays of light coming through the lens converge to form a sharp image. The picture is "in focus" or sharpest when this point coincides with the film plane. 2. To change the lens-to-film distance (or the camera-to-subject distance) until the image is sharp.

Focusing ring. The band on the camera lens that, when turned, moves the lens in relation to the film plane, focusing the camera for specific distances.

Frame. 1. A single image in a roll f film. 2. The edges of an image.

F-stop (f-number). A numerical designation (f/2, f/2.8, etc.) indicating the size of the aperture lens opening.

Grain. The particles of silver that make up a photographic image.

Grainy. Describes an image that has a speckled look due to particles of silver clumping together.

Gray card. A card that reflect a known percentage of the light falling on it. Often has a gray side reflecting 18 percent and a white side reflecting 90 percent of the light. Used to take accurate exposure meter readings (meters base their exposures on a gray tone of 18 percent reflectance).

Guide number. A number rating for a flash unit that can be used to calculate the correct exposure for a particular film speed and flash-to-subject distance.

Hand hold. To support the camera with the hands rather than with a tripod or other fixed support.

Highlight. A very light area in a scene, print, or transparency; a very dense, dark area in a negative. Also called a high value.

Hot shoe. A clip on the top of the camera that attaches a flash unit and provides an electrical link to synchronize the flash with the camera shutter, eliminating the need for a sync. cord.

Hyperfocal distance. The distance to the nearest object in focus when the lens is focused on infinity. Setting the lens to focus on this distance instead of on infinity will keep the farthest objects in focus as well as extend the depth of field to include objects closer to the camera.

Incident-light meter. A hand-held exposure meter that measures the amount of light falling on the subject. See also Reflected-light meter.

Indoor film. See Tungsten film.

Infinity. The farthest distance marked on the focusing ring of the lens, generally about 50 feet. When the camera is focused on infinity, all objects at that distance or farther away will be sharp.

Interchangeable lens. A lens that can be removed from the camera and replaced by another lens.

ISO. A numerical rating that indicates the speed of a film. The rating doubles each time the sensitivity of the film doubles.

Latitude. The amount of over- or under-exposure possible without a significant change in the quality of the image.

Lens.One or more pieces of optical glass used to gather and focus light rays to form an image.

Lens element. A single piece of optical glass that acts as a lens or as part of a lens.

Light-emitting diode (LED). A display in the viewfinder of some cameras that gives you information about aperture and shutter speed settings or other exposure data.

Light meter. See Exposure meter.

Long-focal-length lens. A lens that provides a narrow angle of view of a scene, including less of a scene than a lens of normal focal length and therefore magnifying objects in the image. Often called telephoto lens.

Macro lens. A lens specifically designed for close-up photography and capable of good optical performance when used very close to a subject.

Macro photography. Production of images on film that are life-size or larger.

Macro-zoom lens. A lens that has close-focusing capability plus variable focal length.

Manual exposure. A nonautomatic mode of camera operation in which the photographer sets both the aperture and the shutter speed.

Manual flash. A nonautomatic mode of flash operation in which the photographer controls the exposure by adjusting the size of the lens opening.

Meter. 1. See Exposure meter. 2.To take a light reading with a meter.

Middle gray. A standard average gray tone of 18 percent reflectance. See Gray card.

Midtone. An area of medium brightness, neither a very dark shadow nor a very bright highlight.

Mirror. A polished metallic reflector set inside the camera body at a 45-degree angle to the lens to reflect the image up onto the focusing screen. When a picture is taken, the mirror moves so that light can reach the film.

Neutral-density filter. A piece of dark glass or plastic p[laced in front of the camera lens to decrease the intensity of light entering the lens. It affects exposure, but not color.

Normal-focal-length lens (standard lens). A lens that provides about the same angle of view of a scene as the human eye and that does not unduly magnify or diminish the relative size of objects in the image.

Open up. To increase the size of the lens aperture. The opposite of stop down.

Overexpose. To expose film to too much light. Overexposing film produces a transparency that is too light.

Polarizing filter. A filter placed in front of the camera lens to reduce reflections from nonmetallic surfaces like glass or water.

Programmed automatic. A mode of automatic exposure in which the camera sets both the shutter speed and the aperture for a normal exposure.

Push. To expose film at a higher film speed rating than normal, then to compensate in part for the resulting underexposure by giving greater development than normal. This permits shooting at a dimmer light level, a faster shutter speed, or a smaller aperture than would otherwise be possible.s

Reciprocity effect (reciprocity failure). A shift in the color balance or the darkness of an image caused by very long or very short exposures.

Reflected-light meter. An exposure meter (hand held or built into the camera) that reads the amount of light reflected from the subject. See also Incident-light meter.

Reflex camera. a camera with a built-in mirror that reflects the scene being photographed onto a ground-glass viewing screen. See Single-lens reflex, Twin-lens reflex.

Reversal film. Photographic film that produces a positive image (transparency/slide) upon exposure and development.

Rewind crank. A device, usually on the top of the camera, for winding film back into a cassette once it has been exposed.

Sharp. Describes an image or part of an image that shows crisp, precise texture and detail. The opposite of blurred or soft.

Short-focal-length lens (wide-angle lens). A lens that provides a wide angle of view of a scene, including more of the subject area than a lens of normal focal length.

Shutter. A device in the camera that opens and closes to expose the film to light for a measured amount of time.

Shutter-priority mode. An automatic exposure system in which the photographer sets the shutter speed and the camera selects the aperture (f-stop) for normal exposure.

Shutter release. The mechanism, usually a button on the top of the camera, that activates the shutter to expose the film.

Shutter speed control. The camera control that selects the length of time the film is exposed to light.

Single-lens reflex (SLR). A type of camera with one lens which is used both for viewing and for taking the picture. a mirror inside the camera reflects the image up into the viewfinder. When the picture is taken, this mirror moves out of the way,allowing the light entering the lens to travel directly to the film.

Slide. See Transparency.

Slow. The opposite of fast.

SLR. See Single-lens reflex.

Soft. Describes an image that is blurred or out of focus. The opposite of sharp.

Speed. 1. The relative ability of a lens to transmit light. Measured by the largest aperture at which the lens can be used. A fast lens has a larger maximum aperture and can transmit more light than a slow one. 2. The relative sensitivity to light of photographic film. See Film speed.

Spot meter. An exposure meter with a narrow angle of view, used to measure the amount of light reading from a small portion of the scene being photographed.

Stop. 1. An aperture setting that indicates the size of the lens opening. 2. A change in exposure by a factor of two. Changing the aperture from one setting to the next doubles or halves the amount of light reading the film. Changing the shutter speed from one setting to the next does the same thing. Either changes the exposure one stop.

Stop down. To decrease the size f the lens aperture. The opposite of open up.

Strobe. See Electronic flash.

Sync (or synchronization cord). an electrical wire that links a flash unit to a camera' shutter release mechanism.

Synchronize. To cause a flash unit to fire while the camera shutter is open.

Telephoto effect. A change in perspective caused by using a long-focal-length lens very far from all parts of a scene. Objects appear closer together than they really are.

Telephoto lens. See Long-focal-length lens.

Through-the-lens meter (TTL meter). An exposure meter built into the camera that takes light readings through the lens.

Transparency (slide). A positive image on a clear film base viewed by passing light through from behind with a projector or light box. Usually in color.

Tripod. A three-legged support for the camera.

TTL. Abbreviation for through the lens, as in through-the-lens viewing or metering.

Tungsten film. Color film that has been balanced to produce colors that look natural when exposed in tungsten light, specifically light of 3200 K color temperature. Type A tungsten film has a slightly different balance for use with photoflood bulbs of 3400 K color temperature.

Twin-lens reflex. A camera in which two lenses are mounted above one another. The bottom (taking ) lens forms an image to expose the film. The top (viewing) lens forms an image that reflects upward onto a ground glass viewing screen. Abbreviated TLR.

Underexpose. To expose film to too little light. Underexposing film produces a transparency that is too dark.

Wide-angle distortion. A change in perspective caused by using a wide-angle (short-focal-length) lens very close to a subject. Objects appear stretched out or farther apart than they really are.

Wide-angle lens. See Short-focal-length lens.

Zoom lens. A lens with several moving elements which can be used to produce a continuous range of focal lengths.