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by Russell McMahon

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I'm familiar with the lens design limitations imposed by the flange-to-focal-plane distance. But what constraints are caused by the width of the lens mount (that is, the size of the hole in the camera body)? Clearly there's the fact that if your lens mount needs electrical contacts, they have to fit in somehow and you need to make arrangements for a diaphragm if the lens needs one. But what other limitations are imposed? For example, does it limit the maximum aperture of a lens?

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Do you mean the width of the ring itself, or the total width of the mount? –  Håkon K. Olafsen Apr 21 '12 at 6:54
Clarified (I think). –  James Youngman Apr 21 '12 at 20:05
Regarding aperture, the only thing that really drives the size of the maximum aperture is the front lens element, since relative aperture is based on entrance pupil, which is observed through the front of the lens. With the proper post-diaphragm element groups, you can control the size of the light cone pretty much as you please, so long as it maintains the proper the size of the lens mount shouldn't really affect lens design limits. It might affect sensor design limits because of the image circle size. –  jrista Apr 22 '12 at 13:45

1 Answer 1

A larger lens mount makes it easier to design compatible tilt/shift lenses.

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