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01-19-2013, 02:21 AM   #1
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DIY crop mode?

I would like to try mounting a "small format" (eg K-mount, Canon EF, Nikon FX etc) lens on a Pentax 645 or other MF camera with the hope this would work similar to the "crop mode" feature of the latest Canon, Nikon and Sony DSLRs that enable mounting of legacy APS-C mount lenses on their full frame bodies albeit only using a small part of the sensor. Do you know of any adapter that can do this?

01-19-2013, 03:32 AM   #2
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Not really practical:

Registration distance, 645 Mount = 70.87mm
Registration distance K-mount = 45.46mm

That is, the image formed by a K-mount lens placed in level with the 645 flange would form about 2 cm in front of the 645 sensor. In other words, you will need some optical element that can carry the image over that extra distance.

It works with FX and DX because these cameras have the same registration distance.
01-19-2013, 05:31 AM   #3
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Original Poster
thanks for clearing this up
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