f number

1. 1.

   the ratio of the focal length to the diameter of a (camera) lens system

   Synonymsfocal ratiostop numberspeed

   Broaderratio

Questions about f number

What does f number mean?

f number means "the ratio of the focal length to the diameter of a (camera) lens system".

What is another word for f number?

Close synonyms include focal ratio, stop number, speed. Each sense on this page lists its own synonyms, because a word with several meanings rarely has one substitute that works for all of them.