39mm Screw Mount Lenses: Leica vs. Pentax

[Neil Poulsen]

Early Leica and Pentax cameras used a 39mm screw mount in their cameras.

To my question, can Leica and Pentax lenses for these cameras be used interchangeably?

 

[DREW WILEY]

I can't find any answer on either the Pentax forum or on Camera Quest. You might need the help of a Paleontologist.

 

[Dan Fromm]

Drew, Asahiflex lenses were in 37mm screw mount. Asahiflexes were SLRs. Can't use Leica thread mount lenses -- body too deep, mount too small. Asahiflex lenses could probably be adapted to LTM bodies. All that's needed it an extension tube that's long enough, threaded male M39x26 tpi and female M37xI don't know what at the other. Can't imagine why anyone would bother, wouldn't be surprised if has been done.

 

[Chan Tran]

I thought Pentax is 42mm.

 

[John Koehrer]

^^^^^^^^^^^ Sure enough are, by golly.
Canon and Voightlander made some \, Olympus made only one..........40mm f2.8 pretty uncommon beyond that there were a couple of less regarded makers

 

[Dan Fromm]

I thought Pentax is 42mm.

Mostly, but the Asahiflex was different.

 

[DREW WILEY]

Yes, Dan. Ahasiflex was 39mm. But these cameras had a mirror in them, as you noted, so the spacing distance of the lens would be completely different than the Leica rangefinder cameras. Certain of these Pentax lenses evolved into the M42 screw mount size for sake of early Asahi Pentax prism-style SLR's - that's as far back as I go in my own experience.

 

[aw614]

The Pentax 43mm 1.9 came in LTM is the only one I can't think of that can be used on a Leica

 

[reddesert]

The concept of flange focal distance will be useful for the OP: https://en.wikipedia.org/wiki/Flange_focal_distance

There are M39 mount SLRs, but they are early Soviet SLRs (Zenit), not Pentax. Lenses do not interchange between Leica M39 and Zenit M39 in a useful way because the flange distance is wrong.

 

[ph]

The flange distance is essential. You might also note that to use non RF optics on rangefinder cameras, they will need proper couplings to the ragefinder lever wheel. Electronic couplings or coding to achieve compenation for less well correted lens aberrations will not be needed for well designed lenses.

Cheap Chinese adapters will usually do but the aapted lenses often do not focus exactly according to their scales, but a little bit beyond the infinity mark Wide angles are most finicky. Novoflex mounts and adapters are usually exact.

p.

 

[darinwc]

Yes, Dan. Ahasiflex was 39mm. But these cameras had a mirror in them, as you noted, so the spacing distance of the lens would be completely different than the Leica rangefinder cameras. Certain of these Pentax lenses evolved into the M42 screw mount size for sake of early Asahi Pentax prism-style SLR's - that's as far back as I go in my own experience.

No. Asahiflex cameras were 37mm screw mount. They were simple designs and not as fast as Leica, Canon, Nikkor LTM lenses. At least the 50mm. There was no wide angle at the time. There was an 85mm f1.9 but not as good as the others.

There was one LTM lens made by Pentax as a special edition. A 43mm.

The later m42 and k mount Pentax lenses were mostly excellent and a few compete with Leica optics.

 

[DREW WILEY]

Thanks, Darin. Just a typo on my behalf. The Pentax Forum details six different 37mm Asahiflex lenses.