from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A camera lens aperture setting that corresponds to an f-number.
  • n. See f-number.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Any of the discrete steps or stopping points for adjusting the aperture of a lens, either marked on a ring on the lens and adjusted by rotating that ring or marked in the display of a digital camera and adjusted by buttons or touch-sensitive controls.


f(ocal length) + stop.
(American Heritage® Dictionary of the English Language, Fourth Edition)



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  • The "F" refers to focal length.

    March 26, 2011