Glossary of Terms

Teleconverter – 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.

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

Terabyte (TB) –one thousand million bytes of computer data.

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

TIFF (tagged image file format) – a lossless uncompressed file format preferred by professionals seeking high-quality images for publication.

Tone – the lightness of an area of an image. Highlights have light tones and shadows have dark tones.

Tracking focus – a sophisticated autofocus system that tracks continuously a moving subject.

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

Tritone – an image produced by the use of three colours.

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

Tungsten – 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.

Twin-lens reflex – 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.