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05-07-2011, 02:41 AM   #1
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Wide-angle, big aperture?

So I know a little bit about lenses and the way they work.
I know that the aperture is actually a ratio of focal length to the size of the maximum. Hence, lenses like the Canon 85/1.2 is massive, requiring an aperture of around 71mm.

But what I am wondering is, why do lenses like my DA15 and other wide angles so slow? 15mm could have a aperture of 15mm or f/1 and still be roughly the same size.
Obviously there is more too this, but I don't know. Can anyone explain it to me?

05-07-2011, 02:47 AM   #2
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This should answer the question :Angénieux retrofocus - Wikipedia, the free encyclopedia

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