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Definition of "f-number" []

  • The numerical value of the relative aperture. If the relative aperture is f8, 8 is the f-number and indicates that the focal length of the lens is 8 times the size of the lens aperture (noun)

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Use "f-number" in a sentence
  • "Blaker explained this in another book, Field Photography (1976): ... at significant magnifications the choice of f-number is ... nearly always a matter for compromise between depth of field needs and the resolution of fine detail in the image."
  • "If your camera has manual controls, you can add more light to your shots by opening the aperture more widely (using a smaller f-number) and slowing the shutter speed (to, say, 1/125 or even 1/60 of a second)."
  • "Blaker explained this in another book, Field Photography 1976:...at significant magnifications the choice of f-number is...nearly always a matter for compromise between depth of field needs and the resolution of fine detail in the image."
  • "Each "stop" is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop."
  • "The literal interpretation of the f/N notation for f-number N is as an arithmetic expression for the effective aperture diameter (input pupil diameter), the focal length divided by the f-number: D = f/N. Noooo!!!"