Definitions for f-numberˈɛfˌnʌm bər

This page provides all possible meanings and translations of the word f-number


  1. f-number(Noun)

    The ratio of the focal length of a lens to its diameter; a measure of the light-gathering ability of the lens.


  1. F-number

    In optics, the f-number of an optical system is the ratio of the lens's focal length to the diameter of the entrance pupil. It is a dimensionless number that is a quantitative measure of lens speed, and an important concept in photography.


Find a translation for the f-number definition in other languages:

Select another language:

Discuss these f-number definitions with the community:

Word of the Day

Would you like us to send you a FREE new word definition delivered to your inbox daily?

Please enter your email address:     


Use the citation below to add this definition to your bibliography:


"f-number." STANDS4 LLC, 2015. Web. 13 Oct. 2015. <>.

Are we missing a good definition for f-number? Don't keep it to yourself...

Nearby & related entries:

Alternative searches for f-number:

Thanks for your vote! We truly appreciate your support.