f-number

noun
f-num·ber | \ ˈef-ˌnəm-bər \

Definition of f-number 

1 : the ratio of the focal length to the aperture in an optical system

2 : a number following the symbol f/ that expresses the effectiveness of the aperture of a camera lens in relation to brightness of image so that the smaller the number the brighter the image and therefore the shorter the exposure required

First Known Use of f-number

1898, in the meaning defined at sense 1

History and Etymology for f-number

focal length

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Dictionary Entries near f-number

fndg

fndn

fndr

f-number

fo

FO

Fo

Statistics for f-number

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Time Traveler for f-number

The first known use of f-number was in 1898

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Britannica.com: Encyclopedia article about f-number

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