| 单词 | focal length |
| 释义 | > as lemmasfocal length focal length n. the distance from a lens, lens system, or curved mirror to its focus along its focal axis; = focal distance n. 1. ΘΚΠ the world > relative properties > number > geometry > curve > [noun] > with regard to distance focal length1682 focal distance1705 power of a point1872 curve or line of striction1875 1682Focall length [see sense 3]. 1682 J. Flamsteed Let. 7 July in Corr. (1997) II. 17 The distinctnesse is as the focall length of the one object glasse is to the like length of the other. 1732 S. Fuller Pract. Astron. 154 The Radius of the Sphere, on which the Concave Metalline Speculum must be ground.., will be about Ten Feet, and consequently its Focal Length will be about 62 Inches. 1754 Philos. Trans. 1753 (Royal Soc.) 48 170 An object-lens whose focal length is a little less. 1831 D. Brewster Treat. Optics xlii. 357 The great speculum has a focal length of 25 feet, and a diameter of 15 inches. 1940 N.Y. Times 1 Sept. x. 5/1 Most amateurs dream of owning a huge battery of lenses—as many as ten or twenty—of differing focal lengths. 1992 Irish Times 9 Jan. 9/4 The project involved testing the mirror's focal length so that fine adjustments to its surface could be made. 2005 TNT Mag. 7 Mar. 83/2 The angle of view depends on the focal length of the lens and the film format/digital setting. < as lemmas |
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