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

noun Photography

The ratio of the focal length of a camera lens to the diameter of the aperture being used for a particular shot (e.g. f8, indicating that the focal length is eight times the diameter).The f-numbers marked on a lens are only truly accurate when the lens is focused at infinity....

All these f-numbers, focal lengths, film speeds and apertures are actually really simple to get to grips with once you understand how they relate to each other and to the finished picture.
The higher f-numbers mean the diameter of the lens can be smaller, so the lens, using only 20% to 25% as much material, will cost less and weigh less.

Origin

Early 20th century: from f (denoting the focal length) and number.

单词	f-number
释义	f-number noun Photography The ratio of the focal length of a camera lens to the diameter of the aperture being used for a particular shot (e.g. f8, indicating that the focal length is eight times the diameter).The f-numbers marked on a lens are only truly accurate when the lens is focused at infinity.... All these f-numbers, focal lengths, film speeds and apertures are actually really simple to get to grips with once you understand how they relate to each other and to the finished picture. The higher f-numbers mean the diameter of the lens can be smaller, so the lens, using only 20% to 25% as much material, will cost less and weigh less. Origin Early 20th century: from f (denoting the focal length) and number.
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