Share this entry

Share this page

f-number

Line breaks: f-number

Definition of f-number in English:

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).
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.

Definition of f-number in:

Share this entry

Share this page

 

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.

Get more from Oxford Dictionaries

Subscribe to remove adverts and access premium resources

Word of the day snarf
Pronunciation: snɑːf
verb
eat or drink quickly or greedily