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06-12-2012, 04:32 PM   #46
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QuoteOriginally posted by drougge Quote
Well, that is certainly a form of "not straight", though not the one I meant. The lens is rotated compared to how it's supposed to be mounted, leaving what should be the upper and lower part of the hood on the sides like that. You can cut it off, but I think using the lens on a camera where it mounts properly would be a better solution.
I don't understand why the rotation of the lens matters. Shouldn't it just be the field of view of the body that matters ?
FYI, the Pentax K-r body has 1.5x crop ratio, and T3i has 1.6x crop ratio. Could that be part of the problem ?

I don't want to cut off the lens hood, because I would not be able to use the lens cap anymore. And due to its shape, this lens cannot take filters so the front element would be completely unprotected in the bag.

06-12-2012, 05:15 PM   #47
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QuoteOriginally posted by madbrain Quote
I don't understand why the rotation of the lens matters. Shouldn't it just be the field of view of the body that matters ?
FYI, the Pentax K-r body has 1.5x crop ratio, and T3i has 1.6x crop ratio. Could that be part of the problem ?
It's not rotation of the lens that matters per se, but rather rotation of a petal hood. A petal hood must match the alignment (typically rectangular) of the image sensor/film plane, otherwise it will get in the way of the light path. In the case of a petal lens hood integrated into a lens, lens alignment definitely becomes an issue in that scenario by proxy.
06-12-2012, 05:50 PM   #48
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QuoteOriginally posted by nater Quote
It's not rotation of the lens that matters per se, but rather rotation of a petal hood. A petal hood must match the alignment (typically rectangular) of the image sensor/film plane, otherwise it will get in the way of the light path. In the case of a petal lens hood integrated into a lens, lens alignment definitely becomes an issue in that scenario by proxy.
Thanks, that makes sense now ... I don't know if there are any PK-EOS adapters that do not rotate the lens. Time to do more research.

Edit: did some googling. Looks like the rotation is done on purpose on the PK-EOS adapter, because otherwise the aperture lever on Pentax lenseswould prevent mounting on Canon bodies. Some people have performed "leverectomies" on their Pentax lenses (ugh), but I obviously don't want to do that since I still shoot with a Pentax body too.

So, it looks like I will not be able to use the Samyang 8mm with my Canon body after all .
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