ØWiki說明:Total amount of light
allowed to fall on the photographic medium (photographic film or image sensor)
during the process of taking a photograph.
Ø光量的大小,通常會使用單位Photometric
or luminous exposure,例如:photometric units。進光量的計算則是光與曝光時間的乘積,可以經由光圈(aperture),快門(shutter speed),和底片的感光度來控制。