Glossary of Photographic Terms

ANAMORPHIC LENS  

A lens that compresses or elongates its images either vertically or horizontally.

ANGULAR COVERAGE

The field of view (in degrees) seen/covered by the lens.

A.N.S.I.

American National Standards Institute.

APERTURE

Opening of the lens which is expressed as a fraction of the focal length ( f/stop).

ASA

The American Standards Association.

ASTIGMATISM

The lens' inability to bring radial and tangential lines into common focus on to the image circle.

AVAILABLE LIGHT

The light condition that the photographer finds at the subject position.

BACK FOCUS

When the lens is focused at infinity, the distance from the rear surface of the lens to the focal plane is called BACK FOCUS.

BACK LIGHT

Illumination from a source behind the subject (the subject is placed between the camera and the light source). This type of lighting tends to silhouette the subject.

BARREL DISTORTION

A DISTORTION that causes the lines near the edges of the image bowing-out.

BELLOWS

The center section (usually in large format cameras) which connects the front (lens) to the back (camera body).  The bellows is made of leather, cloth or plastic, and is accordion-pleated for flexibility and is lighttight.

BELLOWS EXTENSION

An additional extension that extend the length of the bellows (beyond that required for infinity focus) to enable the photographer to focus at a closer distances to the subject.

BETWEEN-THE-LENS SHUTTER

A shutter incorporated in the lens and is designed to operate in a space between the lens elements.

BOUNCE LIGHT

Reflected (indirect) light; A light source that is directed away from the subject toward some nearby light-toned surface which reflects the light to the subject..

BRACKET

To make a number of exposures in addition to the one consider to be "normal." Some of these exposures are to be greater than the "normal" and some less than the "normal." Bracketing significantly increases the chance of getting a exposure near perfect.

BULB

A marked setting (B) that permits the shutter to be kept open for an indefinite period of time.

CABLE RELEASE

A long flexible cable that screws into a special threaded socket on the shutter release. The CABLE RELEASE is used to release the shutter remotely.

CAMERA

 In Latin language camera means room. An instrument used by photographs for taking pictures. A CAMERA consist of at least a lighttight box, a lens and some device or provision for holding the film in position.

CC FILTERS

Color Compensating filters, used in color photography to modify the color balance of the image.

CIRCLE OF CONFUSION

The tiny blurred circle of light that a lens forms as an image of a point of light placed at the subject position. 

CLOSE-UP LENS

A supplementary lens that is placed over a camera lens to shortens its focal length and therefore produce closer-than-normal focusing.

CLOSE-UP PHOTOGRAPHY

 The techniques of using macro (micro) lenses, supplementary lenses, extension tubes, bellows, etc., to photograph subjects at closer ranges than normal focusing adjustment of an ordinary camera will allow.

COCKING THE SHUTTER

Winding the shutter mainspring before making the exposure.

COLD TONES

Bluish or greenish tinge in the black-and-white image.

COLOR TEMPERATURE

A standard for defining the color of light based on its similarity to the light color emitted by a black body heated to a known temperature and is measured in degrees Kelvin or "Kelvins." For example, daylight has a color temperature of from about 5500^oK. to 6000^oK.

COMPLEMENTARY COLORS

Any two colors that, in the subtractive system, when mixed produce black or dark neutral gray; and in the additive system, any two colors that when mixed produce white light.

CONCAVE

The side of a spherical surface seen from the inside.

CONTACT PRINTING

The strip of negative is placed in contact with the printing paper and held in that position in a  printing frame when the print is made. When contact prints are made usually, the contact sheet is given an average exposure to match the exposure of the majority of the images.

CONTINUOUS SPECTRUM

Light that contains all the visible wavelengths or colors.

CONTINUOUS TONE

Describes an image containing a gradation of grays as well as black-and-white.

CONTRAST

Density difference between the highlights and the shadows, usually of adjacent areas of the image.

CONVEX

Bulging.  The opposite of CONCAVE.  The surface of a sphere seen from outside.

CROP

Trimming or covering the borders of an image to improve the composition.

CROSS LIGHT

Light shining on the subject from one side.

CURTAIN SHUTTER

A shutter variety in which a opening in a sheet of metal or cloth is made to travel past the film surface to effect the exposure.

DAYLIGHT

Sunlight or skylight or a mixture of the two types.  Daylight has a color temperature of from about 5500^oK. to 6000^oK.

DEPTH OF FIELD

The region of reasonably sharp focus in front and beyond the subject position.  The boundaries of the depth of field are called the near limit and the far limit.

DEPTH OF FIELD SCALE

A calibrated scale, ring or chart, usually a part of the camera lens mount, that indicates the depth of field for any distance and aperture setting.

DEPTH OF FOCUS

The space including the focal plane of the lens through which the film can be moved closer or farther away from the lens, and still produce a reasonably sharp image.

DIAPHRAGM

The thin metal leaves that can be adjusted to control the size of the lens aperture.

DIFFRACTION

The light rays bending around the edge of an object.

DIFFUSION

The random scattering of light rays either by being transmitted through a translucent medium or being reflected from a matte surface.

DIN

Deutsche Industrie Normen.  The German system of film speed.

DIOPTER

It identifies the power of a lens and it expresses the reciprocal of the lens focal length in meters. A negative DIOPTER number represents a diverging lens and a positive one represents a converging lens. For example, a close-up (positive) lens with a focal length of 50 cm (1/2 meter) would be labeled a +2 lens.

DISCONTINUOUS SPECTRUM

Light radiation that is either missing certain colors (wavelengths) or contains a negligible amounts.

DISPERSION

The separation of a light ray into its component colors (i.e. by a prism).

DISTORTION

Linear distortion or curvelinear distortion is an aberration of the lens that is characterized by variable magnification of the image.  The effect increases as it gets closer to the edges of the image and will cause straight lines near the edges of the subject to show as curved lines.  There are two forms of distortions,  PINCUSHION and BARREL distortion.

EASEL

Normally an adjustable metal frame that holds printing paper flat for exposure under the enlarger, and allows adjustments of the width of the picture borders.

EXPOSURE

Subjecting a photosensitive material to light.

EXPOSURE FACTOR

A multiplier number indicating the exposure increase required (i.e. when using a filter). For example, 4X means four times the normal exposure is required.

EXPOSURE INDEX

Usually referred to as the film speed, a number indicating relative light sensitivity of a given film.

EXPOSURE METER

A device used to measure the brightness of the subject or illumination level at the subject position. This information and the film speed can be used to determine appropriate camera aperture and shutter speed settings.

EXTENSION TUBES

A set of rings or tubes of varying lengths, used between the camera body and lens to permit focusing the lens on subjects at close range. 

FAILURE OF THE RECIPROCITY LAW

When sensitive emulsions are subjected to extremely intense or extremely dim exposing lights they require more total exposure than would be predicted by the Reciprocity Law.  See RECIPROCITY LAW.

FAST

Films of high sensitivity or lenses of large relative aperture.  This term is also sometimes applied to unusually sensitive papers.

FEATHERING A LIGHT

The method of evening out the illumination across a scene by directing the central beam of a light toward the objects furthest from the camera. this allows the objects closest to the camera to be illuminated by the less intense margins of the beam.

FILL LIGHT

Light directed into the shadow areas of the scene or subject to reduce the contrast between the highlights and the shadows of the scene.

FILM SPEED

The relative sensitivity of film to light, represented by the film's ISO number.

FILTER

(1) Passing light through some material which absorbs selected wavelengths, colors, polarized portions of the light, or modifies the appearance of the subject. A filter can be a sheet or disc of plastic, glass or other material, which can be placed on the lens or in front of the light source.

FISH-EYE-LENS 

A super wide-angle lens, or lens attachment, with a field of view of approximately 180^o.  Images produced by a Fish-eye lens (or a lens attachment) are circular.

FLARE

Unwanted light, which is not a part of the controlled image light, which passes through the lens and strikes the film. Flare light usually caused by dirty lens surfaces, scratches or chips in the glass, or bright surfaces inside the camera.

FLASH

Term used for any photographic light source which produces a very brilliant and brief pulse of light.

FLASH SYNCHRONIZATION

The synchronization of firing of the flash and the shutter release so that the peak flash intensity occurs while the shutter is open.

FLOOD

Usually an incandescent light source that is designed to illuminate an area with light of relatively uniform intensity.

f/NUMBER

A number that represents the aperture diameter of a lens as a fraction of the focal length.

FOCAL DISTANCE

The distance from the lens to the plane of the focused image (where the film is located in the camera).

FOCAL LENGTH

Usually, the FOCAL DISTANCE when the lens is focused on INFINITY.

FOCAL PLANE SHUTTER

This is the CURTAIN SHUTTER which is in the camera body just in front of the film plane.

FOCUS

To adjust the lens on a camera so that a sharp image is formed on the film plane.

FRAME

Adjusting the position of the camera in order to contain the image within the boundaries of the viewfinder.

GRAIN

The granular texture of a photograph caused by the clumping of the silver particles, which is usually more visible when the photograph is enlarged.

GRAY

The intermediate tones of a black-and-white image. 

GRAY CARD

A reflective card (usually 18% gray), used as a meter target in the determination of exposure.

GRAY SCALE

A strip of film or paper which shows different shades of gray, used in testing the sensitivity and contrast characteristics of photographic materials.

HIGHLIGHTS

The brightest areas of light in the image.

HOT-SPOT

An undesirable area of brilliant illumination  produced by the concentrated central beam of a spotlight or flood light in a studio setting.

HYPERFOCAL DISTANCE

The distance from the camera to the nearest plane of sharpest focus when the far plane of the depth of field is at infinity.

IMAGE

The photographic representation produced of the subject photographed.  

INCIDENT LIGHT

All forms of light which reach the subject.

INCIDENT METER

A device designed to measure the incident light intensity.

INFRARED

The invisible rays just beyond the red end of the visible spectrum; these waves are longer than those of the spectrum colors, but shorter than radio waves and have a penetrating heating effect.

KELVIN TEMPERATURE

A scale of temperature measured in degrees Celsius from absolute zero (-273.15^oC). In photography, another name for COLOR TEMPERATURE.

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