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02-26-2014, 12:09 AM   #1
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PENTAX-A* 645 600mm F5.6 with M45 Lens Mount


I bought a Pentax 600mm f/5.6 for my 645N and it arrived from Japan today...

One problem...

There is a different mount on the back of the camera. It is a M45 mount. The lens cap actually screws on slightly.

The eBay auction was inaccurate and advertised it as fitting 645 and 645D cameras.

Does anyone know of adaptors that could get me from this M45 mount to say a Nikon F mount or Canon EF mount? I've been hunting for this lens forever... even if I can't use it on my 645N I'd like to be able to at least get it mounted on a Canon, Nikon or Sigma SA mount.

Any advice would be appreciated.

When I inspected the interior part of the M45 mount I kind of see remnants of the original 645 mount, but I can't tell if there has been some serious machining at that level or if this is some kind of 645 to M45 adaptor. My initial take is that the previous owner hacked the 645 mount to get it to a M45 mount.

02-27-2014, 03:54 AM   #2
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excuse me what´s a "M45" mount?. Do you mean a classical M42 screw mount ?
02-28-2014, 05:03 PM   #3
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do you have pictures?
03-02-2014, 01:26 PM   #4
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There was a K-mount 600 F/5.6 that would be hopeless for you.
There was a 645D mount that could've been adapted down to a screw-mount.

If it's the second, then you're fine, just remove adapters.
If it's the first, remove the screw mount adapter. You can adapt it to the Canon mount but unless you got a really good deal I'd be demanding my money back.


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600mm, 600mm f5.6, 645d, 645n, camera, canon, f5.6 with m45, lens, m45, m45 lens, medium format, nikon, pentax-a* 645 600mm
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