[Aejap]

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Hello!
I know there are a few threads here about M39 to M42 Adapter but I was not able to find a definitive answer to what I'm looking for:

I have a Spotmatic and would like to put a Jupiter-9 85mm lens (

Youtu.be

Youtu.be

) on it. The lens has an M39 mount and it came with an Adapter to M42, which also looks exactly like the one he shows in the video at 7:09. On various Adapters to other lens mounts (Sony NEX, Canon EF etc.) it screws on nicely and the lens is great to use on these digital cameras. Focus to infinity is also possible.

However, on the Spotmatic it won't screw on properly, much like it is described in this thread.

So my question is: Does anyone know of an Adapter for M39 lenses to M42 cameras that will actually work on the Spotmatic?

Thanks for any suggestions!

[Not a Number]

Check these threads out:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/61648-m39-...ml#post2323773
Did Pentax Asahi make a m39 to k mount converter? - PentaxForums.com

[Aejap]

Thanks!

I have read the threads you linked, and while they cover similar problems, they unfortunately don't include a solution for my situation.
The first link covers the different M39 mount versions. I don't have a problem with M39, the adapter fits perfectly on the lens (as can be seen in the video I linked). The problem is exclusively with the M42 side of the Adapter not fitting in the Spotmatic.
The second link is about putting a M39 lens on a Pentax camera with K-Mount, which is not what I'm trying to do.

Thanks anyway!

[ismaelg]

Hello,

Make sure the adapter is in fact M42 and not T2 mount which is also 42mm size but different thread pitch. I think M42 is 1mm pitch and T2 is 0.75mm or the other way around.

Thanks,
Ismael

[Not a Number]

If you get your hands on the genuine Asahi M42 to M39 adapter it should fit your Spotmatic since that was what it was made for.

Third party adapters can be touch and go. I have a Fotodiox M42 to M39 adapter that fits fine on my Asahi Pentax Auto Bellows (M42) and Japan made Pentax branded M42 to K-mount adapter. But it won't fit in the Philippines made Pentax branded M42 to K-mount adapter. Yet I have no problems with any of my screwmount lenses in the Philippines made adapter. It also fits fine in my Fotodiox M42 to Minolta SR adapter. Adapters from Fotodiox are usually of good quality.

[kypfer]

Hello!
I know there are a few threads here about M39 to M42 Adapter but I was not able to find a definitive answer to what I'm looking for:
I have a Spotmatic and would like to put a Jupiter-9 85mm lens (the first, silver version) on it. The lens has an M39 mount and it came with an Adapter to M42, which also looks exactly like the one he shows in the video at 7:09. On various Adapters to other lens mounts (Sony NEX, Canon EF etc.) it screws on nicely and the lens is great to use on these digital cameras. Focus to infinity is also possible.
However, on the Spotmatic it won't screw on properly, much like it is described in this thread.
So my question is: Does anyone know of an Adapter for M39 lenses to M42 cameras that will actually work on the Spotmatic?
Thanks for any suggestions!

I've got (and have owned for many years) an adaptor as shown in the video which works perfectly with my old Industar-50 (not 50-2), which is what it was bought for … it works, can't say more than that.
If your M39-M42 adaptor won't screw into a Spotmatic (or M42-PK adaptor) the external thread of the M39-M42 adaptor has got to be faulty … possibly just a burr or distorted thread, so worth examining with a magnifier. Check especially around the "unscrewing slots", which should always face away from the lens, just in case the adaptor does jam on and you want to use a different lens!
My Industar-50 is the only lens I have from my days with a Zenit 3m (bought new in '69) and I still enjoy it's quirkiness
My Jupiter-9 is in L39 fitting, unfortunately, but so worth having I bought a Samsung mirrorless and L39 adaptor for it





Don't you just love backward compatibility

[Aejap]

Thanks everyone!

@ismaelg - The weird thing is that the M42 Adapter fits nicely into any third-party adapter for M42 -> NEX, EOS etc. so I know for sure that it's not a T2 adapter or anything else with a different pitch.
@Not a Number - Huh, interesting! I haven't come across an original Asahi one yet, I guess that would be the best option but probably the hardest to obtain. I might try to buy a fotodiox one next and hope that it fits. Weird that the fit of these adapters vary so much...
@kypfer - I don't think the outer thread is faulty because I can use it without problems on any third-party M42 -> NEX/EOS adapter... I have an Industar-50 as well, but the M42 version, and I agree, its an interesting little lens!

[stevebrot]

The lens has an M39 mount and it came with an Adapter to M42,

If it is M39, the thread is M39 (LTM) and was intended for use on a rangefinder camera (e.g. FED, Kiev, etc.) and is not adaptable to your SLR (wrong flange registration distance).


Steve

[Aejap]

If it is M39, the thread is M39 (LTM) and was intended for use on a rangefinder camera (e.g. FED, Kiev, etc.) and is not adaptable to your SLR (wrong flange registration distance).


Steve

Since this is a soviet lens, it is not the Leica M39 standard but the Zenit M39 standard. Leica (LTM) would be wrong flange distance, yes, but the Zenit M39 standard is made for SLR cameras and has a flange registration distance of 45.2, so there is no problem with that.

[stevebrot]

Since this is a soviet lens, it is not the Leica M39 standard but the Zenit M39 standard. Leica (LTM) would be wrong flange distance,

I beg to differ, being the owner of both type lenses* and in the interest of accuracy, I will dispute your claim. Zenit M42 lenses are bog standard M42. The rangefinder lenses are LTM (I have adapted them to M mount and shot with them on my Voigtlander R3M) and are made to the shorter flange distance.


Steve

* Have a good size collection of former Soviet glass and cameras (mostly rangefinders, but also one K-mount Zenit).

[kypfer]

I beg to differ, being the owner of both type lenses* and in the interest of accuracy, I will dispute your claim. Zenit M42 lenses are bog standard M42. The rangefinder lenses are LTM (I have adapted them to M mount and shot with them on my Voigtlander R3M) and are made to the shorter flange distance.
Steve
* Have a good size collection of former Soviet glass and cameras (mostly rangefinders, but also one K-mount Zenit).

You seem to be missing the point … many Soviet lenses were also made in "Zenit 39mm" fitting, an slr fitting with a similar flange distance to M42 and PK (yes, I know they're not 'identical') but using the same 39mm thread as the screw-fit Leica lenses and their Soviet counterparts. Cameras like this included the Zenit 3m (basically an earlier version of the Zenit B but without the instant return mirror or lever wind).
I owned a 3m from new in the late '60's and used Soviet r/f cameras regularly, especially my favourite, the Zorki 6, well into the '90's. The lenses are mechanically interchangeable, same thread, but optically incompatible!
If I read things correctly, it's a Jupiter-9 in this 'Zenit 39mm' fitting that the OP has and is wanting to fit on his Pentax … shouldn't be a problem with a properly made adaptor.
As with the 135mm Jupiter-11, the body shape of the slr lenses is noticeably different to that of the r/f lens, though the optics are alleged to be the same.
I may not have a "good sized collection", but I do have an original 1968 UK price list and illustrated catalogue, the Jupiter-9 was available in "Zenith" (Z39), "Fed" (L39) and "Zenith E" (M42) fittings, the two former at £22.7.6 and the latter at £27.19.6, (GBP) recommended retail prices! These probably included UK tax. The 135mm Jupiter-11 was also available in all three variants, I don't have the Z39 but I have the other two

[Aejap]

You seem to be missing the point … many Soviet lenses were also made in "Zenit 39mm" fitting, an slr fitting with a similar flange distance to M42 and PK (yes, I know they're not 'identical') but using the same 39mm thread as the screw-fit Leica lenses and their Soviet counterparts. Cameras like this included the Zenit 3m (basically an earlier version of the Zenit B but without the instant return mirror or lever wind).
I owned a 3m from new in the late '60's and used Soviet r/f cameras regularly, especially my favourite, the Zorki 6, well into the '90's. The lenses are mechanically interchangeable, same thread, but optically incompatible!
If I read things correctly, it's a Jupiter-9 in this 'Zenit 39mm' fitting that the OP has and is wanting to fit on his Pentax … shouldn't be a problem with a properly made adaptor.
As with the 135mm Jupiter-11, the body shape of the slr lenses is noticeably different to that of the r/f lens, though the optics are alleged to be the same.
I may not have a "good sized collection", but I do have an original 1968 UK price list and illustrated catalogue, the Jupiter-9 was available in "Zenith" (Z39), "Fed" (L39) and "Zenith E" (M42) fittings, the two former at £22.7.6 and the latter at £27.19.6, (GBP) recommended retail prices! These probably included UK tax. The 135mm Jupiter-11 was also available in all three variants, I don't have the Z39 but I have the other two

The rangefinder lenses are LTM

Yes that is true, but this lens is not a rangefinder lens; it was made for the M39 Zenit cameras.
As I said before, I can focus to distant objects (probably infinity?) on a Sony E-mount digital camera with the exact same adapter setup as shown in the video I linked above at 7:34. That would be impossible with a rangefinder/LTM lens.

If I read things correctly, it's a Jupiter-9 in this 'Zenit 39mm' fitting that the OP has and is wanting to fit on his Pentax … shouldn't be a problem with a properly made adaptor.

Exactly! And the M39->M42 adapter that was on the lens fits on any M42-NEX adapter etc, but doesn't screw onto the Spotmatic directly for some reason, that's why I am looking for a properly made adapter that will allow me to do this. When I try to put it on the Spotmatic it feels like the thread pitch is wrong. All other M42 lenses I own fit on the camera nicely, so there is nothing wrong with the camera, and the Jupiter-9 with it's M42 adapter fits nicely on all M42 mounts I have except for the Spotmatic. I don't get why, but this specific adapter seems to be incompatible with the camera.

In the thread from 2014 that I linked above there was a very similar problem to mine but with a M42 -> Pentax K adapter instead of the Spotmatic, and there were speculations that they both are technically within specified tolerances, but on the opposite ends, so they end up not fitting (which seems weird to me because preventing this from happening is the whole point of having specified tolerances, but might be possible anyway I guess?)

I may have to look for the genuine Asahi one that @Not_a_Number mentioned. So far I wasn't able to find much info on it.

[stevebrot]

an slr fitting with a similar flange distance to M42 and PK (yes, I know they're not 'identical')

Yes, there is a Zenit SLR flavor of M39 (Zenit SLR)...sorry for the confusion. The rangefinder lens threads are identical and will even mount on those cameras, but without the ability to attain focus.

Note: Important to remember that the M39 Zenit cameras have a flange distance of 45.2mm such that adapted M42 lenses won't attain infinity focus. FWIW, I stupidly passed on purchase of a working KMZ Krystal at a gear swap a few years ago. Dumb me...too cheap to put out the $50 USD being asked.


Steve

[Aejap]

Okay, here is a little update:

I found an original Asahi M39-M42 Adapter on eBay and received it today. I also bought a few more M39 SLR mount lenses, a Zenit 3M and a Zenit 3 in the meantime. One of the M39 lenses, a Jupiter-11 135mm f/4, also came with one of these black generic M39-M42 adapters. The other lenses are a Mir-1 37mm f/2.8 and a Helios 44 58mm f/2.

Here is what I found out, and I hope that this will counter some of the misinformation that circulates on here and around the internet about these three different thread mounts. All of the following, if not explicitly stated otherwise, is tested first-hand experience and can be easily confirmed, so it is not just speculation.

- M42 (the Mount the Spotmatic uses) has a flange focal distance of 45.5mm
- M39 LTM (LTM = "Leica Thread Mount", which is the Leica rangefinder standard) has a flange focal distance of 28.8mm
- M39 SLR (sometimes also called "M39 Zenit" - basically the soviets took the M39 LTM mount and moved it to the front to make place for the mirror of the Zenit cameras) has a flange focal distance of 45.2mm

The lens mounts of all of my lenses I listed above are M39 SLR. As far as I can tell, variants of them were built for either M39 LTM or M42, or both, as well.
Here is an example of the Jupiter-11 135mm both in M39 LTM and M39 SLR. The version I have is the one to the right, and as you can see, the LTM version has a longer tube at the rear to compensate for the shorter flange focus distance of the LTM mount.

You can put LTM lenses on Zenit bodies and vice versa, but obviously the focus would be way off:
- Putting an LTM lens on a Zenit body would basically be like using the lens with a Macro Extension Tube.
- Putting a Zenit lens on a LTM body would work exactly opposite. (I don't have any LTM lenses so I can't test how much off it is, but I assume that focusing would not be possible at all because all focusing distances would be "behind infinity".)



The Asahi Adapter I bought is labelled as "Asahi Leica Mount Adaptor A" and the original packaging which was included with the adapter I bought says this on it:

"For use of Leica mount Lenses on the PENTAX camera body (close-ups only)"

This is a bit misleading, as it is also usable with M39 SLR lenses, and even better so in my opinion. Since the difference between LTM lenses and M42 is 16.7mm, and between M39 SLR lenses and M42 it is only 0.3mm, it is like a much smaller macro extension tube, and the "close-up only" property of it is much less severe.

This Asahi adapter (obviously) fits nicely onto the Spotmatic, focusing for example with the Jupiter-9 85mm works up to about 4m, so for portrait photography it works really well.

I also have a digital camera (Sony) and both a Fotga M42 adapter and a Metabones EF adapter for it.
Both of them (for the Metabones I used a M42-EF Adapter ring) result in about the same focusing range like with the Spotmatic.
When used with an M42 lens like any of my Takumars, focusing to infinity works perfectly, confirming the adapters maintaining the correct flange distance.

Interestingly, the black, generic adapters are way less off. Using the M39 SLR lenses with one of these adapter rings and one of the two ways I have to put them on the Sony, focusing to infinity almost works.
There is a significant difference between the original Asahi adapter and the generic black ones concerning flange distance, which makes sense since the Asahi one was not made with M39 SLR lenses in mind.
Using any of the adapter combinations on my Sony but with the black M39-M42 adapter instead of the Asahi one, I can focus on buildings approximately 100m away without problems, and when stopped down, even much further than that.

This potentially also explains, why these black adapters don't fit onto the Spotmatic; it was not made to accommodate the deeper adapter which is needed to get the lens closer to the film plane.
I don't know if they fit on other M42 cameras, but there are other people who had similar issues, for example here with a Pentax M42-K adapter.



In conclusion:
- M39 LTM and M39 Zenit is not the same.
- A lot of the soviet lenses available were made for both mounts, which adds to the confusion.
- There is a genuine Asahi M39-M42 adapter, but it can only be used for focusing on close distances when using M39 SLR lenses (very close distances when using LTM lenses).
- The more modern black generic M39-M42 adapter rings enable focusing to far distances, but do not fit on all M42 bodies/adapters out there, the Spotmatic and Pentax M42-K adapter being two examples.

[kypfer]

Okay, here is a little update:

I found an original Asahi M39-M42 Adapter on eBay and received it today. I also bought a few more M39 SLR mount lenses, a Zenit 3M and a Zenit 3 in the meantime. One of the M39 lenses, a Jupiter-11 135mm f/4, also came with one of these black generic M39-M42 adapters. The other lenses are a Mir-1 37mm f/2.8 and a Helios 44-2 58mm f/2.

Here is what I found out, and I hope that this will counter some of the misinformation that circulates on here and around the internet about these three different thread mounts. All of the following, if not explicitly stated otherwise, is tested first-hand experience and can be easily confirmed, so it is not just speculation.

- M42 (the Mount the Spotmatic uses) has a flange focal distance of 45.5mm
- M39 LTM (LTM = "Leica Thread Mount", which is the Leica rangefinder standard) has a flange focal distance of 28.8mm
- M39 SLR (sometimes also called "M39 Zenit" - basically the soviets took the M39 LTM mount and moved it to the front to make place for the mirror of the Zenit cameras) has a flange focal distance of 45.2mm

The lens mounts of all of my lenses I listed above are M39 SLR. As far as I can tell, variants of them were built for either M39 LTM or M42, or both, as well.

Am I mis-reading you? Surely the Helios 44-2 is M42 fitting … the Z39 version is the Helios 44 (no -2).
I always wanted to try a MIR-1, but couldn't afford one at the time and "made do" with s/h Soligor and Enna lenses!
Enjoy