英语词汇“f-number”的英英意思、用法、释义、翻译、读音、例句、短语、词组-英语词典

f-number n. Photography and Optics the ratio of the focal length of a lens, telescope, etc., to the effective diameter of the aperture, used typically to express its light-gathering power (a lower f-number corresponding to a larger aperture); cf. relative aperture n. at relative n., adj., and adv. Compounds.

ΚΠ

1898 Photogr. Times May 215/1 When the distance focused upon is equal to ten times the square of the focal length divided by the f number, the sharp focus becomes infinite in depth.

1918 Camera Craft Aug. 325/2 How comes it that the buyer so often finds the f-number of the aperture to be less than it is marked?

1958 Pop. Mech. Apr. 203/1 The lower a lens' f-number, the greater its light-passing ability.

2001 F. Watson in P. Moore 2002 Yearbk. Astron. ii. 225 The speed with which an extended object like a nebula can be recorded depends not on the aperture of the telescope..but only on its focal ratio, or f/number.

单词	f-number
释义	> as lemmas f-number f-number n. Photography and Optics the ratio of the focal length of a lens, telescope, etc., to the effective diameter of the aperture, used typically to express its light-gathering power (a lower f-number corresponding to a larger aperture); cf. relative aperture n. at relative n., adj., and adv. Compounds. ΚΠ 1898 Photogr. Times May 215/1 When the distance focused upon is equal to ten times the square of the focal length divided by the f number, the sharp focus becomes infinite in depth. 1918 Camera Craft Aug. 325/2 How comes it that the buyer so often finds the f-number of the aperture to be less than it is marked? 1958 Pop. Mech. Apr. 203/1 The lower a lens' f-number, the greater its light-passing ability. 2001 F. Watson in P. Moore 2002 Yearbk. Astron. ii. 225 The speed with which an extended object like a nebula can be recorded depends not on the aperture of the telescope..but only on its focal ratio, or f/number. extracted from Fn. < as lemmas
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> as lemmas