Adaptation of Light

This is the ability of the eye to adjust to changes in luminance by making the pupil larger or smaller. It means we can see correctly across a wide range of illuminance values. The time taken to adapt in this way is largely determined by the luminances at the start and end of the adaptation process. This adaptation takes place very quickly from dark to light (brightness adaptation) but much more slowly (30 minutes or more) from light to dark (darkness adaptation).