Middle left stick

Calculator stick

C-41

The chemistry used to process most colour negative films.

Cable release

A flexible cable used to release a camera shutter without causing movement and consequent blurring of an image.  It is normally used in conjunction with a tripod and a slow shutter speed.

Cache

RAM used to hold computer data recently read from a mass storage device. Its purpose is to speed up processing.

Camera format

The size and aspect ratio of an image produced on film or a digital sensor by a camera body. The format is determined by the physical dimensions of the focal plane or image sensor.

Camera movement

Movement of a camera during the exposure period, perhaps causing loss of detail or blurring.

Camera obscura

The camera obscura consists of a darkened room with a small aperture opened in one wall. An inverted image of the scene outside the room is projected through the aperture and onto the opposite (usually white) wall. Eventually a converging lens was fitted in to the aperture to produce clearer and sharper images.

Capacity

The quantity of computer data that can be held by a storage device, usually quoted in MB or GB or TB.

Catadioptric lens

A long focal length lens using mirrors within its construction. The mirrors allow a long focal length to be achieved within a comparatively short lens barrel. This type of lens is also known as a mirror or reflex lens.

Catch-light

Small specular reflections of a light source usually seen in the eyes in portraiture. Lack of catch lights in portraits may be regarded as a deficiency.

CCD

Silicon chip used as an electronic sensor to replace film in a digital camera. It has electrodes arranged in a rectangular array. The electrodes a light sensitive and correspond to pixels. The light level measured by each electrode is turned into a digital code.

CD-R

Compact disk used as a read-only memory (CD-ROM). Data can be written onto it only once.

CD-RW

A rewritable compact disk onto which data can be written any number of times.

Centre-weighted metering

Exposure determination system commonly found in SLRs and DSLRs giving greater emphasis to brightness in the centre of the field of view.

Changing bag

A light-proof black fabric bag used to handle film and other light-sensitive materials in daylight. Most have two separate layers equipped with zips, and a pair of sleeves with elastic armholes.

Chroma

The purity of a colour measured as a product of hue and brightness, or the degree of departure of a colour from the neutral. Colours having a low chroma value are usually described as weak, whereas those with a high chroma are said to be strong or highly saturated.

Chromogenic films

B&W films that can be processed using standard C-41 colour chemistry to produce monochrome prints.

Circle of confusion

The diameter of a spot that cannot be distinguished from a point in an image at a normal viewing distance of 250mm. This measurement is an essential element in calculating depth of field.

Cloning

Copying one part of an image directly to another area.

CMYK

Cyan, magenta, yellow and black colour model.

Colorimeter

An instrument for measuring colour, and used to calibrate a computer monitor.

Colour balance

An adjustment made in a photographic process to ensure that neutral greys in a subject remain neutral in an image.

Colour cast

A false predominance or bias of a particular colour spread evenly throughout an image, and usually most apparent in light neutral tones.

Colour gamut

The range of colours a particular device or reproduction system is able to produce.

Colour management

The process of controlling the colours in an image reproduction system such that they are repeatable and acceptably accurate. Key components of colour management are monitor and printer calibration.

Colour rendering index (CRI)

A quantitative measure of the ability of a light source to reproduce colours - measured against their perceived appearance in natural light or under a reference illuminant. natural sunlight is considered to have a CRI of 100.

Colour space

A defined range of colours producible by an output device.

Colour temperature

Measure of the colour of a light source in terms of physical temperature (degrees Kelvin) of a black body radiator. Daylight approximates to 5,400oK and a sunset to 2,800oK.

Coma

The inability of a lens to render off-axis point sources of light as circular. Points appear as comet-shaped blurs, from which the name coma is derived, with the tails flaring toward the centre of an image. The problem is minimized by closing down the lens diaphragm.The aberration is difficult to eliminate in wide-angle lenses with large maximum apertures.

CompactFlash card

A memory card designed to store images within a digital camera. Many digital cameras with PC card interfaces use this storage technology which conforms to a standard supported by the CompactFlash Association. CompactFlash is ATA compatible and the cards fit Type II or Type III slots when used with a passive adapter.

Complementary colours

Pairs of colours of light which, when combined in equal proportions, produce white light - ie cyan and red, yellow and blue.

Compression

The process of encoding digital files in a space-efficient manner. Compression algorithms remove unnecessary information from files in a way that allows it later to be replaced. No compression of physical storage is involved.

Contact sheet

A same-size print of all the negatives on a roll of film used to select images for enlargement.

Contrast

The brightness range in a scene, or the difference in brightness between adjacent areas of tone. Also, the rate at which processed film density increases with greater exposure.

Convergence

The appearance of parallel lines in a view, as seen in an image, when photographed from an angle.

CPU (Central Processing Unit)

An electronic component that controls the principal functions of a computer or camera. Automatic cameras have at least one CPU to control essential functions. More sophisticated models may have numerous CPUs to handle exposure, autofocus etc. Some autofocus lenses also have built-in CPUs to communicate information such as focal length, focus distance, and lens type to the body of the camera.

Crop

To use or remove part of an image typically to improve composition or make it fit a given space.

Cropped sensor

A sensor in a digital camera having dimensions smaller than those of the comparable film-based format.

Cut and paste

To remove a selected part of an image, or other digital file, and store it temporarily in a memory before reusing in, or pasting it to, another location.

Please Support OPS

Donate using PayPal
Amount:
Go to top