different screw mounts

[FrankS]

I'm aware of the leica standard M39 and the Pentax standard 42mm screw mounts. Are there others? A 100mm f4 Hanimex brand screw mount lens that my brother-in-law bought last week at a camera show (on my recommendation) does not screw into his Fed2e camera (bought from me). He says the lens is slightly too big to fit. Could this lens be for another camera system that has a 40mm diameter or perhaps an imperial thread? A confused mind would like to know!

 

[FrankS]

Nothing in between? From what he described, the fit was jsut a teenie bit too big, not 3mm. Perhaps the threads are buggered. I told him that I'd buy it from him at his purchase price ($10) becasue I feel responsible. I'm supposed to be the expert on this stuff. If it indeed does turn out to be a 42mm thread, I've got a nice Spotmatic to put it on.

 

[Sonnar Brian]

The Argus C3 screw mount was smaller: 37mm(?) The Miranda screw mount was bigger: 44mm. The original Asahiflex screw mount of the '50s was smaller than 42mm; it was 37mm. If the threads are damaged, as they were on the LTM Nikkor 105mm F2.5 that I picked up (at a great price) they seem too big to screw into their intended mount.

 

[FrankS]

Can you suggest the best way of dealing with messed up threads? File the offending/damaged threads?

 

[Sonnar Brian]

I was able to repair the threads on the Nikkor, doing what G'man has said. I used a fine file on the bad parts, then used a 39mm steel retaining ring. I think that came off of an old Bellows -or something in the Junkpile-. I forced the retaining ring on and off of the lens. The lens went onto the Canonator for a test, and it worked well. I put an LTM to M adapter on it and use it with the M3; the 90mm lines are very close to 100% coverage for the 105.

 

[jlw]

I'm aware of the leica standard M39 and the Pentax standard 42mm screw mounts. Are there others? A 100mm f4 Hanimex brand screw mount lens that my brother-in-law bought last week at a camera show (on my recommendation) does not screw into his Fed2e camera (bought from me). He says the lens is slightly too big to fit. Could this lens be for another camera system that has a 40mm diameter or perhaps an imperial thread? A confused mind would like to know!

Could this be a T-mount lens? This was a simple (no auto diaphragm or meter coupling) interchangeable mount system popular with makers of third-party SLR lenses and accessories. The male T mount that would be found on the lens would be a thread with a diameter of about 41.8mm and a very fine pitch (much finer than the Leica or Pentax threads.)

If it's a T-mount lens, all you've got to do is order a T-mount adapter for the SLR you want to use -- many larger camera stores can still supply them.

 

[ChrisN]

I have an Elmar 90/4 (LTM) that will fit my Canon's but won't screw completely into my Mir (Zorki). The pitch on the thread is apparently slightly different. According to this page http://www.graphics.cornell.edu/~westin/misc/mounts-alphabetical.html the Leica is M39 x 26 tpi and the Canon is M39 x 1 (engineering types please explain?). No listing for the Zorki. He does list a Practiflex mount as M40 x 1 - maybe that's what you've found.

 

[Seele]

I have an Elmar 90/4 (LTM) that will fit my Canon's but won't screw completely into my Mir (Zorki). The pitch on the thread is apparently slightly different. According to this page http://www.graphics.cornell.edu/~westin/misc/mounts-alphabetical.html the Leica is M39 x 26 tpi and the Canon is M39 x 1 (engineering types please explain?). No listing for the Zorki. He does list a Practiflex mount as M40 x 1 - maybe that's what you've found.

According to Dechert, Canon tried to make its cameras as compatible with the Leica as possible, and what it could do was to measure the screw thread - a few turns of it - so as to replicate it. It was naturally assumed that Leica would have used a sensible thread pitch of 1mm, but Canon never thought that Leica used a silly thread of 26TPI.

After realising that Canon developed the "slop mount" where it used the minimum number of turns, and the maximum clearance between the threads, so as to take both threads. Later on Canon adopted the Leica standard so no problem.

 

[Heath]

All my Hanimex lenses are M-42. The hanimex cmpany was originally an import and export company that was the major shipper of the Praktica range. Then they badge engineered lenses for the Praktica system, which of course were the M-42 mount. I think what he has is a nice M-42 SLR lens.

Heath