aperture

The aperture of a camera lens is the size of the hole through whuch light enters the camera. This controls the amount of light entering the camera, so has to be larger in darker conditions. It also affects the depth of field (what is in focus simultaneously) as the outer areas of the lens have more distortion, so that a smaller apperture leads to sharper images even if they are not at the exact focal point ... and also, becasue your pupil acts as apperture control in your eye, the reason why it is easier to read in bright light.

Defined on page 356

Used on page 356