In article ,
Armando wrote:

Ric Trexell wrote:
Many times repair manuals are available on ebay for your camera. The mount
must be exactly what the manufacturer calls for in the distance from the
mount to the film plane. A depth micrometer guage will almost be needed for
this. A repair shop would use a collimator to make sure the focus is
correct. If you don't have these things, make sure any spacers are replaced
where they came from. However, since one mount is different from the next,
even getting spacers replaced exactly might not make for a good set up. Ric
in Wisconsin.

Thank You for Your answer.
I think I won't make any change on my camera.
The reason why I bought the bayonet is a little "play" of some heavy
lenses I had noticed. I use the camera for astroimaging and during long
exposures the rotation of the camera (to have no stars motion on the
frame) together with the weight of the lens could cause a little shift
of the lens... But I need to be sure this problem occurs since I have to
make some pressure to be able to manually "shift" the lens attached to
the bayonet.

Thank You again
Armando

John Craig of Craig Camera sells user and repair manuals -- literally
thousands of them. If what you are looking for isn't on his website
http://www.craigcamera.com you can contact him directly and request
it.

On his repair manual page he lists various M645 models -- just scroll
down to the "M"s http://http://www.craigcamera.com/lit_newrep.htm

He sells both originals and xerox copies, often (but not always) for
less than they can be found on ebay.

Hope this helps.