Definition of f-number in English:

f-number

Syllabification: f-num·ber

noun

Photography
  • The ratio of the focal length of a camera lens to the diameter of the aperture being used for a particular shot (e.g., f8, indicating that the focal length is eight times the diameter).
    More example sentences
    • The f-numbers marked on a lens are only truly accurate when the lens is focused at infinity.
    • All these f-numbers, focal lengths, film speeds and apertures are actually really simple to get to grips with once you understand how they relate to each other and to the finished picture.
    • The higher f-numbers mean the diameter of the lens can be smaller, so the lens, using only 20% to 25% as much material, will cost less and weigh less.

Origin

early 20th century: from f (denoting the focal length) and number.

More definitions of f-number

Definition of f-number in:

Get more from Oxford Dictionaries

Subscribe to remove ads and access premium resources

Word of the day kerf
Pronunciation: kərf
noun
a slit made by cutting with a saw