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05-27-2009, 03:46 PM   #1
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M39 Leica mount adapter

I'm toying with the idea of acquiring an M39 to M42 adapter in order to use my ancient collapsible Leitz 50mm lens & assorted Russian M39 lenses on my *ist DS body by screwing the adapter onto my M42 adapter. Besides probably not being able to focus to infinity, not having encountered anyone discussing this particular endeavor, are there any potential problems I'm not considering?

05-27-2009, 06:57 PM   #2
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I have an M39 to M42 adapter that came with my Jupiter 9. It works fine.

I assume you know that there is both a Leica M39 and a Russian M39?

The Russian M39 has the same registration distance as the M42 mount (except for the lenses they made for range finders that are the same as the Leica lens' registration distance). Making adaptation to Pentax quite easy.


The Leica stuff would be good for close focus only.
05-27-2009, 10:50 PM   #3
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QuoteOriginally posted by konraDarnok Quote

The Russian M39 has the same registration distance as the M42 mount (except for the lenses they made for range finders that are the same as the Leica lens' registration distance). Making adaptation to Pentax quite easy.


T
The M39 lenses I have are rangefinder lenses (for a Zorki "Leica copy" I have).
03-22-2013, 09:53 AM   #4
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How about an adapter for the newer M Mount Lens (Current Leica mount)?

03-22-2013, 10:17 AM   #5
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I made an adaptor using a donor K-Mount from a dead off brand zoom. I machined a sleeve with the M39 whitworth thread, and the sleeve is light tight close tolerance and locked into the K mount by a grubscrew.
However this adaptor is just for bellows use , so does not need to be on register.
Looking at it, I feel it would be not possible to do this with the Russian Register of 45.46 mm ( same as the K mount) and even less possible to do the Leica register of 28.8 mm
The reason is that the outer diameter of the lens body would have to sink into the mount, but the K mount lens side bore is 41 mm.
It is unlikely your lenses would be small enough (less than say 40 mm) to do it.

Edit: Sorry I feel into the old thread trap!
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03-22-2013, 08:15 PM   #6
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QuoteOriginally posted by kivis Quote
How about an adapter for the newer M Mount Lens (Current Leica mount)?
Current Leica M mount is the same as the original from the mid-1950s.

The problem is registration distance. Rangefinder cameras have no mirror box and lens designs for those cameras reflect that feature. As a side effect it is not unusual for some wide angles to have very deep rear elements.


Steve
03-22-2013, 08:29 PM   #7
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QuoteOriginally posted by konraDarnok Quote
I have an M39 to M42 adapter that came with my Jupiter 9. It works fine.

I assume you know that there is both a Leica M39 and a Russian M39?

The Russian M39 has the same registration distance as the M42 mount (except for the lenses they made for range finders that are the same as the Leica lens' registration distance). Making adaptation to Pentax quite easy.


The Leica stuff would be good for close focus only.
QuoteOriginally posted by raymeedc Quote
The M39 lenses I have are rangefinder lenses (for a Zorki "Leica copy" I have).
That sounds about right. There are two M39 mount types. The first and oldest is the Leica thread mount (often abbreviated M39, L39, LTM, or M39 LTM). The second is that found on certain (all Zenit, I believe) FSU (former Soviet Union) 35mm SLRs (often abbreviated M39, M39 Zenit, or M39 SLR) and has the same registration distance as the Praktica/Pentax M42 mount.

A few ways to tell them apart:
  • LTM lenses never have preset apertures...always fully manual
  • LTM lenses always have a metal collar around the rear element that protrudes enough, even at closest focus, to engage the rangefinder arm in the camera body
  • Most (there are a few exceptions) LTM lenses have a minimum focus distance of about 1 meter
The M39-M42 adapters are all intended for use with M39 Zenit lenses.
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03-23-2013, 03:42 AM   #8
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QuoteOriginally posted by stevebrot Quote
The M39-M42 adapters are all intended for use with M39 Zenit lenses.
Steve
Not quite...Asahi Pentax made one back in the day which was most defintely intended for use with Leica M39 (the catalog has the change of focusing distance) and the adaptor was even called (at some times) "Leica Mount Adaptor A".

Edit: Confused the A and B adaptor


Last edited by macTak; 03-23-2013 at 06:38 AM.
03-23-2013, 06:04 AM   #9
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QuoteOriginally posted by macTak Quote
Not quite...Asahi Pentax made one back in the day which was most defintely intended for use with Leica M39 (the catalog has the change of focusing distance) and the adaptor was even called (at some times) "Leica Mount Adaptor B".
That is a new one for me, so I looked it up.

Images of Asahi Pentax L Adapter B at whitemetal.com

And the intended use was? It is hard to say. The mount is M42 female and M39 male. According to the Web page (whitemetal is pretty authoritative), it could be used to mount a Takumar to a LTM body (no close focus and no focus coupling) or to a threaded enlarger lens board. I supposed it could also be used to mount a Takumar to an early Zenit C(S) with loss of infinity focus.

The term "Leica Mount" has historically been a little overused. I have a couple enlarger lenses that are clearly spec'ed by the manufacturers as Leica standard 39mm thread. Those lenses will screw onto a LTM rangefinder body, but that is pretty much the end of their usefulness (no focus mechanism). The only thing they have in common is diameter and thread pitch.

So...I stand corrected in regards to my comment above. I forgot to mention the M39 enlarger lenses. So...to correct the error, here is a revised, open-ended list:
  • M39 LTM (Leica rangefinder registration)
  • M39 Zenit (registration the same as M42 SLR)
  • M39 Enlarger (same diameter and pitch as above, but variable registration distance depending on focal length)
  • M39 Other (there are undoubtedly other applications out there somewhere...)
I suppose a person could attempt to mount their favorite LTM rangefinder lens to their Pentax SLR, but the extra registration distance limits focus to the macro range at best. There is also the issue of rear element clearance. My Jupiter-12 35/2.8 is a cool little lens, but the rear element at infinity sits a mere 2mm from the shutter curtain on an LTM body! I believe there are similar, though less severe, clearance issues with my other M39 LTM lenses. (Bang, bang, bang goes the mirror...)


Steve


FWIW...Canon also marketed M39 adapters. Model A (M39 to FD) and Model B (FD to M39). Isn't Google wonderful?

FWIWA...Pentax also made a Leica mount adapter A (a little clunkier than the above, in bright metal finish)

Last edited by stevebrot; 03-23-2013 at 06:26 AM.
03-23-2013, 06:45 AM   #10
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Steve, I managed to confuse the A and B adaptors. A was M39-M42, B was M42-M39. I recall from Gerjan's book (which I don't have in front of me) that both adaptors were made for a short time in steel, as you mention, but after that were made of black anodised aluminium (at least I think it's aluminium judging from the ones I have). I've seen boxes for these that say "Asahi Pentax Leica Mount Adaptor A", others that say "Asahi Pentax L Mount Adaptor A", and my one from the US distributor Honeywell simply says (as I recall) ("Honeywell Pentax Mount Adaptor A"). Anyway, they are very well made (of course), and still hardly any more expensive than the Chinese generics, so it's not a bad idea to try to get one of them if one wants a M39 adaptor. Here's the page from the Honeywell H2 Operating Manual:


Last edited by macTak; 03-23-2013 at 07:02 AM.
03-23-2013, 07:09 AM   #11
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QuoteOriginally posted by macTak Quote
Steve, I managed to confuse the A and B adaptors. A was M39-M42, B was M42-M39. I recall from Gerjan's book (which I don't have in front of me) that both adaptors were made for a short time in steel, as you mention, but after that were made of black anodised aluminium (at least I think it's aluminium judging from the ones I have). I've seen boxes for these that say "Asahi Pentax Leica Mount Adaptor A", others that say "Asahi Pentax L Mount Adaptor A", and my one from the US distributor Honeywell simply says (as I recall) ("Honeywell Pentax Mount Adaptor A"). Anyway, they are very well made (of course), and still hardly any more expensive than the Chinese generics, so it's not a bad idea to try to get one of them if one wants a M39 adaptor. Here's the page from the catalog:

Very good! I suspected as much, based on the naming of the Canon adapters. I like the table of focus distances. A little over 10" maximum for the 50mm! I was puzzled by the third column, but then it struck me that it is an indication of field of view at maximum focus distance.

Funny, though, the "A" adapter I saw listed on eBay was clearly M42-M39. I think somebody got the boxes mixed up! Funny, too, that Pentax/Honeywell (in the catalog) indicated that the "B" adapter was for close-ups only on LTM bodies. The adapter has insufficient standoff for accurate colimation to LTM. The result is that both close focus and accurate scale focus are lost.

So, you actually own an "A" adapter? Is this as a collector or do you actually shoot LTM glass with your Pentax SLR?


Steve

Last edited by stevebrot; 03-23-2013 at 07:25 AM.
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