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单词 f-number
释义

WordReference Random House Unabridged Dictionary of American English © 2024
f-number  (ef′num′bər),USA pronunciation n. [Optics, Photog.]
  1. Optics, Photographya number corresponding to the ratio of the focal length to the diameter of a lens system, esp. a camera lens. In f/1.4, 1.4 is the f-number and signifies that the focal length of the lens is 1.4 times as great as the diameter. Abbr.: f/, f/, f, f: Also, f number. Also called focal ratio, speed, stop number. Cf. relative aperture.
  • 1890–95

Collins Concise English Dictionary © HarperCollins Publishers::
f-number, f number n
  1. 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
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更新时间：2024/11/11 9:49:30