A supplementary lens inserted between a camera body and a prime lens to increase the focal length of the prime lens by a factor of typically 1.4x or 2x.

A lens with a focal length significantly longer than that of a standard lens.

One million million bytes of computer data.

A small, low-resolution representation of a digital image or graphic, suitable for rapid and convenient downloading or display.

A lossless uncompressed file format preferred by professionals seeking high-quality images for publication.

Subtle shades of white in a photographic image or print, perhaps determined by the presentation medium or the colour of the paper used.

The lightness of an area of an image. Highlights have light tones and shadows have dark tones.

A sophisticated autofocus system that tracks continuously a moving subject.

A film-based image or translucent print made visible by illuminating it from behind so that the eye sees transmitted light.

An image produced by the use of three colours.

Through-the-lens; an in-camera system whereby exposure determination, focusing and viewing take place through the lens of a camera.

An artificial light source based upon heating a tungsten filament, as in domestic lamps. The colour temperature of the light emitted is about 2,800 K, and hence lower and warmer than that of daylight.

A medium format camera using two similar lenses, one above the other. The top one is a reflex viewing lens and the lower one is used to form the photographic image. The two are coupled for focusing purposes.