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06-03-2009, 05:05 AM   #1
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Theoretical limits...

So I'm a bit of a newbie to the 'technical' side of photography. I get the 'stops', shutter speed, ISO, and aperture part. I know what 'register' is, and how mirrored lenses avoid chromatic aberration. But I have a fairly simple question:

What creates the theoretical maximum aperture for a given camera?

In my head, aperture is related to the maximum amount of light a lens can admit, and (in theory at least) can't a lens be made to an arbitrary diameter with focusing optics 'bending' the light onto the film plane? Or is there some kind of physical restriction based on the 'cone' created by the register/mount diameter?

06-03-2009, 05:19 AM   #2
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afaik the size of the lens mount of the camera and registration distance limits the max aperture.
ive heard the canon ef mount is slightly larger and so it could accomodate a 50mm f1.0
canon had an f0.95 for rangefinder cameras because they dont have mirrors so the distance from the lens rear element and the film is very short
06-03-2009, 05:24 AM   #3
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I believe it has more to do with Price vs. Benefits, than the laws of physics.

f1.0 and f.95 lens have been made, extremely expensive for what you gain in
light gathering ability.
06-03-2009, 06:33 AM   #4
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Original Poster
f1.0 and f0.95 haven't been made for the pentax mount so far as I know. I heard this was related to the register distance (makes sense in a way...), but I want to know why? I'm interested in the theoretical limits (in this case...).

This would inform the price vs. benifits scenario (further from theoretical is easier), but what about mirror lenses? Cant they focus as much light as they want onto a focal plane?


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