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Do you need the "best" lens

Started Apr 9, 2022 | Discussions thread
Truman Prevatt
Truman Prevatt Forum Pro • Posts: 14,596
Re: Most enjoyable

Wolf's Head wrote:

Truman Prevatt wrote:

The f number is simply the ratio of the focal length of the lens to the area of the aperture opening.

The diameter of the aperture, surely?

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Yep sorry, the ratio of the focal length to the aperture diameter.  The amount of light goes up linearly with the area and the area goes up linearly to the square of the diameter diameter.  That accounts for the sqrt(2) steps in the f number, f1 to f1.4 to f2 to f2.8, .... You step the f stop from 1.4 to 2 and you half the area of the aperture and half the light.

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Leica Q2 Monochrom Fujifilm X-H1 Fujifilm X-Pro3 Fujifilm XF 35mm F1.4 R Fujifilm XF 50-140mm F2.8 +12 more
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