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Old 10th January 2017
Harold Gough Harold Gough is offline
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Re: M42 thread lenses

Originally Posted by Petrochemist View Post
The usefulness of that depends on the M39 lens.

There where at least 3 M39 mounts, with the registration not standardized on the earliest. Leica used 39mm by 26 tpi (LTM) which apparently mounts on a M39x1 metric thread. Canon used a 39mm 24tpi thread for some of their early lenses.
Many M39 lenses were rangefinder lenses which have to be mounted much closer to the sensor than M42 lenses, if you want infinity focus. Dedicated adapters for these are of course available for MFT.

IIRC all my M39 lenses are actually enlarger lenses, so have no focusing mechanism of their own. I use them with bellows or a helicoid to focus. I can manage infinity focus with all of mine via some combination of adapters but they're generally not challenging focal lengths, but the longest one, either 150mm or 210mm (not sure of the mount of the 210) would be extremely unwieldy and might need two sets of bellows for portrait distances.
Interesting. I may have been lucky. I have some current/recent Schneider HM enlarger lenses in M39. The closest I have in Leitz is a Photar with M40 mount.

I use mine for macro, with one or two helicoids*. My 40mm is always used reversed, so the M42 thread of the adapter is just useful for a cap. That lens gives a pretty go image at distance (m4/3 only) and is stellar for macro, mostly used at FOV 6mm wide. Reversed, it gives reflections off the sensor if you don't insert e.g. a x1.5 TC with a curved rear surface.

The 90mm has a medium format image circle, useful on shift or tilt adapters.

* I also sometimes use the OM film system telescopic tubes (one or two), currently allocated to my Printing-Nikkor 150mm.

The body is willing but the mind is weak.
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