From Longman Dictionary of Contemporary Englishlight meterˈlight ˌmeter noun [countable] TCPan instrument used by a photographer to measure how much light there is
Examples from the Corpus
light meter• A light meter can be used to assess the level of lighting present.• For me, it is the accuracy of the Nikon light meter that really sets it apart.• A Weston light meter in a leather case dangled from his neck like an amulet. 