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08-12-2011, 10:45 AM   #1
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C mount > M43 > K/M42

is this possible? any issues if setup this way?

C mount > M4/3 mount > PK/M42 mount would that work?

08-12-2011, 11:00 AM   #2
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I'm not sure whether it would technically work (I don't see why not), but the image circle covered by C-mount lenses is somewhere between 8mm and 16mm in diameter, and an APS-C sensor is 16x24mm. Therefore, from that lens, any image that you would get would likely not fill the frame -- You would get images that have a circle with the image in the middle and black everywhere else in the frame.
08-12-2011, 11:11 AM   #3
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Oh i see, so it's like some type of lens used on a FF body that has that circle/ lomo effect.
thanks for the info.

i ask since there are no C to PK mount adapter out there.
08-12-2011, 02:29 PM   #4
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There will probably be one for Pentax Q.

08-12-2011, 02:33 PM   #5
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C-mount, used for cine-video cams, has a 25mm thread. You can find a 25-42mm step ring (actually a disc) online for a few bucks. I have one, which I thread into an M42-PK adapter to mount on my Pentax dSLR. But it is useless there.

This has to do with register aka flange-focal distance, the distance from the back of the lens to the camera frame (film or digital). The Pentax register is 45.46mm. The C-mount register is 17.526mm. Assuming they can be made to fit, longer-register lenses can reach infinity focus on shorter-register camera bodies, but not vice-versa. I put a 50mm C-mount lens on my camera. Its furthest focus is about... 50mm, two inches.

This is the basic rule: C-MOUNT LENSES ON DSLRS ARE ONLY GOOD FOR CLOSE-UPS. No Lomo effect, no vignetting -- just ultra-closeup. Don't bother. Or get a Sony NEX (register= 18mm) where C-mount lenses can at least be used for portraits. Or wait for the Q (register= 9.2mm). Have fun!
08-14-2011, 08:24 PM   #6
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thanks RioRico

I guess I'll put my C mount to PK mount to rest & just get other M42's lol
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