OK, Thinking caps on...!

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There ought to be enough accumulative photographic knowledge amongst members of this esteemed forum to solve my problem.
Well, here's hoping anyway.

Problem...To fit a Canon FD lens onto a bellows that has a Pentax M42 x 1 female thread.
The manual aperture ring on the lens must function but data is not fed to the M42 thread.

The obvious answer is to use a FD to M42 adaptor.....very difficult.
According to the Pentax forum such an adaptor has never been commercially produced, if my memory serves, it's to do with the back-focus or some such.
http://photo.net/canon-fd-camera-forum/00XDcp

A few special adaptors may have been made to order by someone like Novaflex.

I have done it on paper using four items, but it is far from ideal. I have used two adaptors, a step-up ring and a male to male coupler.
The step-up ring is M42 x 1 and one of the adaptors is M42 x 0.75, they 'would' fit together with effort, but as I said 'far from ideal'

If you offer any solutions can I please ask that the adaptors are 'available' not theoretical, and not from ebay.
!
 
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Option 1, sell the FD lens and buy an M42 macro equivalent. No need for any adaptors to use your existing bellows.

Option 2, buy FD fit bellows with associated FD>EOS adaptor although you will risk quality degradation unless you have a good quality adaptor.
 
Is this something you need briefly, Dave, or long term? I ask because I have what you need but don't want to lose it permanently.
As your research shows, M42 to FD is unusual because it lengthens the flange distance too far for most practical usage although it's academic on a bellows setup. I made my own many years ago using the back end from an old M42 lens and the front end from an FD extension tube....the two are simply fixed together.

Bob
 
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Is this something you need briefly, Dave, or long term? I ask because I have what you need but don't want to lose it permanently.
As your research shows, M42 to FD is unusual because it lengthens the flange distance too far for most practical usage although it's academic on a bellows setup. I made my own many years ago using the back end from an old M42 lens and the front end from an FD extension tube....the two are simply fixed together.

Bob

Thanks Bob, but it's long term.
 
maybe you could get a rear end cap, cut a hole out, and glue it to the m42 side, or a m42 body cap with a hole in it too
 
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