| 单词 | relative aperture |
| 释义 | > as lemmasrelative aperture relative aperture n. Photography and Optics a measure of the light-collecting power of a lens, telescope, etc., which is usually expressed in terms of its f-number (a lower f-number corresponding to a larger aperture), and is used in determining the exposure needed. ΚΠ 1885 Eng. Mechanic & World of Sci. 17 Apr. 155/2 ‘Gwent’ says he does not know what the ‘equivalent focus’ of his lens is!.. They have a relative aperture, which ‘Gwent’ can easily prove if he will measure the diameters. 1910 Science 16 Dec. 878/2 It would seem useless to construct doublets of greater size with such large relative aperture. 1946 Pop. Sci. Monthly Mar. 122/2 The principal application of the new glass will be in..‘fast’ lenses, such as those having a relative aperture (speed) of f/4.5 and larger. 2000 S. F. Ray in R. E. Jcobson et al. Man. Photogr. (ed. 9) vi. 83/1 Given the light sensitivity of early photographic materials, a primary requirement was an increase in relative aperture. < as lemmas |
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