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{%type%} Definitions

WordNet 3.0Copyright Princeton University


Short "hint"

The ratio of the focal length to the entrance pupil diameter in an optical system or the objective of such a system.

Usage examples (40)
  • On a camera, the f-number is usually adjusted in discrete steps, known as f-stops.
  • Each "stop" is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop.
  • 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...
  • 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... for more
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