Leica M to LTM mount conversion?

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cloak.dagger

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I was wondering if anyone has tried this.

I love my Canon rangefinders, but since there's no fast 21mm, I thought of converting the Zeiss ZM to LTM. If that's possible...

Any hints would be appreciated!
 
if you have a CNC mill, I think it could be done.

Mill a new screw to M39×26tpi, make holes that match with the existing M-bayonette, and screw the new one on.

Just remember the M flange distance is 27.8mm while the LTM is 28.8.
 
Jockos said:
if you have a CNC mill, I think it could be done.

Mill a new screw to M39×26tpi, make holes that match with the existing M-bayonette, and screw the new one on.

Just remember the M flange distance is 27.8mm while the LTM is 28.8.
Click to expand...

Thank you! I know someone who could do this for me and compensate the new mount thickness.

You're a saint.:angel:
 
I sometimes wonder if it might be easier to convert the camera LTM mount to M. Has that ever been tried?


PF


I'll answer myself: 4mm difference in diameter means a whole lot of milling, plus making space for the lens lock. But hey, one can dream.
 
Back to the original subject, I read somewhere (maybe on the Head Bartender's site) that some of the earliest M lenses were actually LTM lenses that had an M mount conversion, and you could remove the M mount to revert them back to LTM. That was before the adapter rings were marketed I assume. Could have even been the inspiration for them.


PF
 
This could only be done with a few lenses because many of the M mount lenses use the flange as the rear of the focusing helicoid. Since the LTM flange is significantly narrower than the M flange, you may not have enough metal to work with to clear the cam and allow RF coupling to the camera, making the whole exercise moot. So, like it has been said, it can be done with enough resources, but only on a select few lenses, all of them slow.

Phil Forrest
 
johannielscom said:
Avenon 21mm 2.8 in LTM isn't fast enough for you?
Click to expand...


I've had a number of older Leica and VC 21mm lenses. Somewhere down the road I picked up the Avenon 21mm. Fantastic lens on both my IIIF and M9. I rarely see it mentioned when discussions on 21mm lenses come up. Being somewhat rare I don't think most people have ever heard of it.
 
Jockos said:
if you have a CNC mill, I think it could be done.

Mill a new screw to M39×26tpi, make holes that match with the existing M-bayonette, and screw the new one on.

Just remember the M flange distance is 27.8mm while the LTM is 28.8.
Click to expand...

If it can be done (easily) it's primarily a lathe operation, not a milling operation, although a vertical mill might be handy to have around to drill some precision holes as needed. One needs to face-off metal on the rear of the lens to increase the lens back focus and then mount a LTM threaded flange (if one can be found). There are many possible complications however, like being able to remove the rear part of the lens that is to be turned since one cannot safely expose the lens glass to the environment of machine tools. One needs also to be sure the rangefinder cam clears any new thread piece added. Any rear surface faced off must also have enough metal on it to accept a facing operation.

Other approaches are possible, but for many lenses it may not be a tractable problem.
 
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