Photographic Terms

Aberration: The inability of a lens to form a perfect, sharp image.
Achromat: A lens that is able to bring two primary colors of the spectrum to the same point of focus.
Acid fixer: A chemical used to neutralize alkali. It is used in the final stage of processing to stop the action of alkaline bath.
Additive color process: A method of producing color images by mixing the three primary colors, red, blue, and green. When mixed in different combinations, these colors can produce any other color.
Aerial perspective: The feeling of depth created by haze. Distant objects are recorded with lighter zones and colors distorted toward blue.
Agitation: The method used to keep chemicals in contact with photographic materials during processing.
Air bells: Bubbles formed on the emulsion surface during processing. They can prevent chemical action.
Airbrushing: Retouching of prints by dyes or pigments sprayed on with high-pressure air.
Anamorphic lens: A lens which is capable of producing images with wider angle of view in one dimension than the other. Distortion occurs in the image, but the lens can be used to project the image in its correct proportions.
Angle of view: The widest angle which a lens can accept light and give an image on the film.
Aperture: Area of lens through which light enters the camera. It is controlled by the diaphragm. Aperture size is calibrated in f-numbers. The larger the number, the smaller the lens opening.
ASA film speed: The speed of a film expressed in arithmetic values determined by American Standard Association.
Aspherical: A surface which is curved and is not spherical. Some lenses are made with such surfaces to correct aberration.
Astigmatism: Lens aberration causing vertical and horizontal lines to focus in different focal planes.

B (Bulb setting): A shutter speed setting that allows time exposures. The shutter stays open as long as the shutter release button remains depressed.
Barrel distortion: Distortion of the image where straight lines in the subject are formed as curved lines. It is most noticeable along the edges of the frame.
Bellows: Light-tight folding sleeve in view cameras that connects the lens to the body. Also an accessory used on smaller formats for close-up work.
Bleaching: Chemical used in processing to convert black silver image into colorless compound such as silver halide.
Bounced flash: Flash illumination reflected from a ceiling or wall being diffused.
Bracketing: Taking extra shots of the same subject with different exposures when unsure of the correct exposure.
Burning-in: Extra exposure given to an area of a print.

Cable release: A cable for releasing the shutter without touching the camera. It reduces the risk of camera shake during exposure.
Camera movements: Used primarily on large format cameras enabling the lens and film to be moved from their standard positions. Such movements allow more depth-of-field, or distortion of image shape.
Chromatic aberration: The inability of a lens to bring light of different colors to a common point of focus.
Circle of confusion: Disks of light in the image produced by a lens from a point source of light. The smaller these discs, the sharper the image.
Close-up attachments: Attachments which allow lenses to focus closer than normal. It can be extension tubes, bellows, or supplementary lenses.
Coated lens: A lens with coated surface such as magnesium fluoride to reduce flare.
Color conversion filters: Color filters used to correct the color temperature of a light source to suit the color balance of films.
Color temperature: Scale measured in Kelvin that is used to express the color quality of a light source.
Complementary colors: Any two colors that, when mixed, will produce white light. The complementary color pairs used in color films and printing processes are red-cyan, green-magenta, and blue-yellow.
Contrast: Difference between light and dark tones in a subject.
Cut film: Large format films which are flat sheets for individual exposures.

Dark slide: Cut film holders used on large format cameras.
Day light film: Color film for use in daylight or flash. These films are balanced to 5400K.
Depth of field: The distance between the nearest and the furthest point in the subject that can be brought to sharp focus.
Depth of field scale: Scales on a lens showing near and far limits of depth-of-field possible with a lens for various focal lengths, apertures and focusing distance.
Depth of focus: The distance the film plane can be moved from a point of focus while still producing an acceptably sharp image.
Developer: Chemical bath that produces a visible image of metallic silver from image formed on film or print.
Diaphragm: The adjustable aperture of a lens which uses a set of curved metal blades to control the size of the aperture.
Diffraction: The way light rays are caused to change direction or become scattered. Mostly noticeable when they pass through a small aperture. Diffraction softens the edge of shadows, as light bends around the edge.
Diffuser: Any substance capable of scattering light. Diffused light is softer and lower in contrast.
DIN: Emulsion rating specified by the German standards association (Deutsche Industrie Norm) . A doubling of speed is indicated by an increase of 3 DIN. 21 DIN= 100 ASA.
Dodging: A term for shading when exposing a print.

Emulsion: The light-sensitive material layer that is coated used in the producing films and printing papers.
Exposure: The amount of light that is allowed to reach film or printing paper. It is controlled by the size of the aperture and the shutter speed.
Exposure latitude: The range which exposure can be varied and still give good results. Greatest latitude is in negative films, the least in printing paper.
Exposure mete: Device for measuring light falling on or reflected from the subject.
Extension tubes: Tubes that can be attached between a lens and camera to extend the range of focusing for close-up photography.

Fill-in flash: Direct or reflected light used to illuminate shadow cast on the main subject.
Filter: A material such as glass or gelatin, which alter the color or light passing through it.
Fisheye lens: Extreme wide-angle lens covering about 180 degrees. It produces distorted images.
Fixing: Chemical used for fixation of an image.
Flare: Scattered light produced by reflections inside the lens. It reduces contrast and shadow detail.
F number: Numbers on the lens which is equivalent to the focal length divided by the diameter of the aperture.
Focal length: The distant between the lens and the position of sharply focused image when the lens is focused at infinity.
Focal plane: Plane on which a lens forms a sharp image when correctly focused.
Focusing: Moving the lens forward or backward relative to the film plane so the rays of light from the subject are brought to sharp focus as an image on the film.

Glare: Intense light reflected off highly reflective surfaces such water and glass. It can be reduced by using polarizing filters.
Graininess: Term used to describe the grainy appearance of a photograph caused by the silver grain clumps or dye images, which form the photographic image.
Ground glass: Translucent screen used for viewing and focusing in large format photography.
Guide number: Numbers given to electronic flash units to express their power. It is used to calculate the aperture needed for subject to light source distances.

High key: Describes an image consisting of light and delicate tones.
Highlights: Brightest and lightest parts of a subject.
Hyperfocal distance: The distance between the camera and the nearest plane of the subject which is sharp when the lens is focused on infinity.

Incident light: Light falling on a subject as distinct from light that is reflected from it.
Incident light reading: Measuring of light falling on the subject by a meter that faces the light source.
Infrared film: A film sensitive to infrared radiation. Used for experimental photography.
IR setting: Special focus setting, marked in red, for infrared photography. Infrared radiation are focused further from the lens than visible light.
ISO: International Standard Organization. An international system of film speed rating.

Kelvin (K): Unit of temperature measurement, starting from absolute zero at -273 degrees. It is used to indicate color balance of light.

Lens: Optical device for forming an image by bending light rays.
Lens barrel: Housing for all the elements of the lens.
Long focus lens: Lenses with focal length greater than the diagonal of the film format it covers.
Low key: Pictures composed mainly of dark tones.

Macro lens: Lens designed to work at close distances, giving up to life-size images.
Macrophotography: Extreme close-up photography from 1:1 (life-size) or higher magnifications to about ten times magnifications.
Midtone: Area of brightness midway between shadows and highlights.
Mirror lens: Lens that uses mirrors within its construction. This allows long focal length lens to fit within a short barrel. Their design requires a fix aperture.

Negative: Image in which light areas of the subject are recorded as dark, and dark areas as light. In color photography, each subject color is represented by its complementary hue.
Neutral density filter: A gray filter used to reduce the amount of light entering the camera. It does not effect the color of the photograph.

Open flash: Flash fired manually between opening and closing the shutter. It is used when the shutter speed is not important because of poor existing light.
Optical axis: Imaginary line passing horizontally through the center of a lens.
Overdevelopment: Excessive development, producing dense, high contrast negatives.
Overexposure: Excessive exposure. On color negatives and prints the result is an increase in overall density. On slides the effect gives lighter results.

Panning: The technique of swinging the camera to follow movement of a subject so the image is of sharp main subject with a blurred background.
Panoramic camera: Camera with a special type of scanning lens to make an image on curved plate or film and cover a very large angle of view.
Penta prism: Five sided prism used to give correct viewing of the image and reflect it on to the focusing screen.
Perspective: System of representing three dimensional objects on a two dimensional surface to give realistic impression of depth.
Polarizes light: Light vibrating in one plane instead of all directions.
Polarizing filter: Filter which is able to absorb polarized light. It reduces or removes reflections, and strengthens color.
Primary colors: The three primary colors, red, blue, and green, can form any other color by additive mixing.
Pushing: Prolonging development of film in order to compensate for underexposure or increase contrast.

Range finder: A camera focusing system that determines the distance between camera and subject.
Reciprocity law: It states that the exposure equals intensity multiplied by duration. This rule fails with very low or high intensities of light.
Reflected light reading: A measurement of light reflected from the subject.
Reflex camera: Camera which uses a mirror to reflect the image.
Resolution: The ability of a lens or film to record fine detail.
Reversal ring: A ring that attaches to the camera, into which the lens is secured with the front element next to the body. This allows greater image magnification and is used in close-up photography.
Ring flash: Electronic flash that fits around the front of a lens, producing shadowless pictures. It is used in macro photography.

Sandwiching: The projection or printing of two or more negative or slides together.
Saturated color: Pure color hue, undiluted by black or white.
Sheet film: Individual pieces of film also known as cut film.
Shutter: Mechanical device used to control the time that light is allowed to expose film or paper. Two main types are between-the-lens shutter and focal plane shutter.
Single lens reflex (SLR): Camera which allow the user to see the exact image formed by the lens, by means of a hinged mirror between the lens and film.
Spot meter: A reflected light meter which measures a small area of the subject.
Standard lens: Lens with a focal length equal to the diagonal of the film format of the camera.
Stop bath: Solution used in processing to stop development by neutralizing the developer.
Stopping down: Reducing the size of the aperture to control exposure or increase depth-of-field.

Telephoto lens: Lens with a focal length greater than the diagonal of the film format.
Tonal range: The range of tones between the lightest and darkest areas.
T setting: Time setting. The shutter remains open after it is pressed and released. It is closed again by pressing the shutter release.
TTL: Through-the-lens metering. It uses cells inside the camera to measure light that has passed through the camera lens.
Tungsten film: Color film balanced to light sources with color temperature of 3200K.
Twin-lens reflex (TLR): Camera with two identical lenses. One is used for viewing and the other for taking pictures.

Underexposure: The result of too little exposure in the camera or when making enlargements. It reduces density and contrast.
Uprating: Rating a film at a higher speed index than normal. It causes underexposure, and is usually compensated for by increasing development time.

View camera: Large format camera with camera movements, taking cut films.
Viewfinder: A screen built into a camera for viewing the subject.
Viewpoint: Position of the camera relative to the subject. The viewpoint is the main factor in determining the perspective of a photograph.
Vigenetting: Darkening or lightening of a picture at the edges.

Wetting agents: Chemical used in the final rinse water to promote even drying of film.
Wide-angle lens: Lens with a focal length shorter than the diagonal of the film format.

Zoom lens: A lens in which focal length can be adjusted over a wide range.

Photographic Terms