This function keeps a shutter open as long as the release button remains depressed.
A send copy of computer files, or the process of making them, for the purpose of protecting against their loss or damage.
Rolls of paper used in a studio to provide plain-coloured backgrounds. The rolls are normally suspended from ceiling mountings or from a pair of adjustable tripod stands equipped with a crossbar. The paper is available in a range of standard widths (typically 2.7 metres) and a large range of colours.
An undesirable artefact of colour gradation produced in computer imaging systems when smooth colour gradients are rendered as blocks of a single colour.
An accessory used with studio light sources to control the direction and spread of the light.
A lens aberration that distorts the shape of images. Magnification increases radially inwards, so the straight edges of a square object bow outwards.
Modern DSLR cameras, and 35mm SLR film cameras, use a bayonet lens fitting which allows a lens to be attached or detatched using a 90-degree turn clockwise or anti-clockwise. Camera manufacturers such as Nikon, Canon, Pentax, Olympus and Sony have their own specific bayonet design so that, for example, a Pentax lens cannot be fitted to a Nikon camera without purchasing a custom-made adaptor.
The number of binary digits assigned to each sample in a sequence of data used to represent an image. 8-bit information registers one of a possible 256 values (colours or densities), whereas 16-bit data registers one of 65,536 values.
A high-capacity optical disk storage system designed to supersede the DVD format. It uses blue laser technology at a wavelength of 405 nanometres to store up to 50 Gigabytes (GB) of data on a single disk.
The aesthetic quality of out-of-focus elements of an image. Good bokeh is achieved when such areas appear soft and well merged. The term originates from the Japanese language.
The diffusion of light from a flashgun by directing it at a suitable reflecting surface such as a white ceiling.
A process of making several shots of the same subject, using incremental changes of aperture or shutter speed, to overcome exposure uncertainties.
The range of tonal variation in an image or scene, usually expressed as a ratio or in f/stops.
An umbrella (brolly) constructed from flexible metal ribs and white or silver reflective fabric that is used to bounce and hence diffuse the light produced by studio flash heads.
An old printing process, patented in the 1850s by Alphonse Poitevin, in which greasy ink on gelatine sensitised by potassium dichromate is used to produce an image.
A memory in an output device, such as a digital camera or printer, which stores data temporarily and feeds it to the device at an appropriate rate.
A darkroom or equivalent digital technique for increasing local contrast and density in an image.