Overexposure

The technical description is a picture where all the tones are squashed into the brighter end of the tonal scale and where the highlights may be completely ‘clipped‘ (lost). The artistic description is a photo that’s lighter than the photographer intended.

Zone System

A system developed by the great landscape photographer Ansel Adams for measuring the light levels throughout a scene and allocating them to ten brightness ‘zones’. The idea was to develop the film to a specific level of contrast that captured the full range of tones and make appropriate artistic interpretations with dodging and burning during the print-making process. It worked well with the very exposure tolerant sheet films of the day, where each negative was processed individually, but it’s mostly of academic interest today since digital sensors don’t offer this extended exposure latitude.

Warmth

A non-technical way of describing the colour temperature of the light in a scene. Pictures taken with a low sun have ‘warmth’ because the light takes on a golden colour. Many photographs – landscapes, for example – can be enhanced with a little additional ‘warmth’.