All L39 RSU threads are NOT created equal !

[arbib]

I have a Zarya with a I-26m (5cm f/2.8), and I just bought a MIR with an I-50 (5cm f/3.5) Rigid...
I can mount both Len's on the Zarya, But I can't mount the I-26m on the MIR. It treads 1/2 turn, then stops, like it is all the on. :bang:

Any Solution to this, or, I can't use the I-26m on the MIR and live with it.. 🙁


The lens is set on 1m when I thread it on to avoid any conflict with the RF arm wedge in the lens mount.

 

[erikhaugsby]

Some of the FSU SLR cameras (like the Zenit 3M, here) were supplied with a threaded mount of 39mm; while the mount itself similar to the Leica L39 mount, the lenses are not interchangeable.
Furthermore, even if you did shoot with the I-50 on your MIR, the back-focus of the lens would be some 20mm behind the film plane of the non-SLR camera.

 

[xayraa33]

Some of the FSU SLR cameras (like the Zenit 3M, here) were supplied with a threaded mount of 39mm; while the mount itself similar to the Leica L39 mount, the lenses are not interchangeable.
Furthermore, even if you did shoot with the I-50 on your MIR, the back-focus of the lens would be some 20mm behind the film plane of the non-SLR camera.

I think the OP is talking about two RF lenses in LTM.
I have Late coated Fed I-10 that only mounts on a Zorki or Nicca/Tower Leica copies.
this could be the QC when made, or that some cameras have more "slop" or thread play on their camera mount to accept less than perfect LTM lenses.
another likely source is very small bit of thread damage on the lens mount of the lens.

 

[raid]

The title for this thread is "All L39 RSU threads are NOT created equal!"

This suggests that all RSU threads are different.

I guess, what was meant was "Not All L39 RSU threads are created equal"

Sorry for being picky. In Probability, word choices can make big differences ...

 

[arbib]

I think the OP is talking about two RF lenses in LTM.
I have Late coated Fed I-10 that only mounts on a Zorki or Nicca/Tower Leica copies.
this could be the QC when made, or that some cameras have more "slop" or thread play on their camera mount to accept less than perfect LTM lenses.
another likely source is very small bit of thread damage on the lens mount of the lens.

Some of the FSU SLR cameras (like the Zenit 3M, here) were supplied with a threaded mount of 39mm; while the mount itself similar to the Leica L39 mount, the lenses are not interchangeable.
Furthermore, even if you did shoot with the I-50 on your MIR, the back-focus of the lens would be some 20mm behind the film plane of the non-SLR camera.

Yes, I am talking about Leica RF L39 len's.
The Lens Thread Slope may be it, I haven't put a glass to the threads yet to look for a dent in the threads. But It (the I-50) DOES mount on the MIR (Zorki 4 body without slow gear train) without a problem. And the Zarya without a problem either.

I wander if the camera mount threads may have a slope issue?..Is that possible. That may explain why I can't mount the I-26m on the MIR, But the Zarya will mount both the I-50 (from the MIR) and the I-26m (came with the Zarya)

 

[xayraa33]

Yes, I am talking about Leica RF L39 len's.
The Lens Thread Slope may be it, I haven't put a glass to the threads yet to look for a dent in the threads. But It (the I-50) DOES mount on the MIR (Zorki 4 body without slow gear train) without a problem. And the Zarya without a problem either.

I wander if the camera mount threads may have a slope issue?..Is that possible. That may explain why I can't mount the I-26m on the MIR, But the Zarya will mount both the I-50 (from the MIR) and the I-26m (came with the Zarya)

I would examine the LTM threads on the I-26m for damage, with a loupe, before anything else.

 

[erikhaugsby]

Yes, I am talking about Leica RF L39 len's.

I should have asked, not assumed. 😱

 

[arbib]

I would examine the LTM threads on the I-26m for damage, with a loupe, before anything else.

After checking the threads with a loop, Indeed, the last 2 threads have been worn down at various spots. The 3rd thread doesn't make a full revolution, and the 2nd thread, wears down to "0" thread about 1/2 way around.....

Damn, Well, at least they are cheap...
I guess I will replace with it a J8, from Fedka., or a I-61/L Zebra.

Thanks for advice on what to look for.

Next Question?

The MIR has a rather long stem comming out of the take-up spool holder in the camera, And it has a spring adjustment. The Question, I don't have a take-up spool for the MIR, and the one from the Zarya is a tad to long and doesn't seat tightly. The Zarya has flanges that I can adjust to make a shug fit with take-up spool. The MIR has no such adjustment flanges..(Zorki 4 without the Slow gears)...
What takeup spool do I need? They seem to look a like to me.

 

[ZorkiKat]

You can be sure that the early FED-1 Industar-10 prewar lenses have a different thread pitch. Their focus pitch is also different.

The later style spool spindle found in Zorki-4, Zenit-C, and Zorki-5 do not have spring fingers which give a friction hold to the spool. Use a Zorki-compatible spool (look for the plastic ones, they will fit nicely too) for your Zarya. Even if it's loose, it will work. FOr some reason I can't see yet, loose spools on these cameras don't seem to hinder operation. The spools would often fall off, and yet with film would work just fine.

 

[xayraa33]

You can be sure that the early FED-1 Industar-10 prewar lenses have a different thread pitch. Their focus pitch is also different.

The later style spool spindle found in Zorki-4, Zenit-C, and Zorki-5 do not have spring fingers which give a friction hold to the spool. Use a Zorki-compatible spool (look for the plastic ones, they will fit nicely too) for your Zarya. Even if it's loose, it will work. FOr some reason I can't see yet, loose spools on these cameras don't seem to hinder operation. The spools would often fall off, and yet with film would work just fine.

This is a late coated postwar Fed I-10 lens that I own . I have seen the this type of Fed I-10 lens, same vintage as mine, fit Leica and Canon cameras perfectly fine.
It is only my specimen that is the oddity.

 

[arbib]

You can be sure that the early FED-1 Industar-10 prewar lenses have a different thread pitch. Their focus pitch is also different.

The later style spool spindle found in Zorki-4, Zenit-C, and Zorki-5 do not have spring fingers which give a friction hold to the spool. Use a Zorki-compatible spool (look for the plastic ones, they will fit nicely too) for your Zarya. Even if it's loose, it will work. FOr some reason I can't see yet, loose spools on these cameras don't seem to hinder operation. The spools would often fall off, and yet with film would work just fine.

Here is a side-by-side of the take-up spool side of the MIR (left) and Zarya (right)...Note that the Zarya Spool holder as 4 wings on it, those are what I slightly pried open to tighten the grip on the take-up spool. sorry for any confusion. I am aware of the spring loaded film grip on the take-up spool.

And a close up of the I-50 (1960)

I am not taking about the "Take-Up" spool, but the Rod or what ever it is called that the take-up spool slide unto to.

FYI..The I-26m is also 1960.

The regular looking take-up spool (like the FED 2 has, won't seat all the way in the MIR.
Q?) Does the spring loaded part on MIR adjust up/down? There is a straight slot for a screw driver to fit. (I don't want to try it until I know that is what it is for)..That would work if it is. I can lower that part a few "mm" so the back cover can close with a tske-up spool inside.

 

[arbib]

I was just reading through the Zorki 4K CLA thread.. And I noticed in a picture of the open back, that the Take-Up spool had NO TIT on the bottom. Is that the kind I Need too?, I am having trouble findind a spool like that.

 

[fanshaw]

The regular looking take-up spool (like the FED 2 has, won't seat all the way in the MIR.
Q?) Does the spring loaded part on MIR adjust up/down? There is a straight slot for a screw driver to fit. (I don't want to try it until I know that is what it is for)..That would work if it is. I can lower that part a few "mm" so the back cover can close with a tske-up spool inside.[/QUOTE]

The spring is to adjust the tension on the take-up drum. It has to slip a little to accommodate the changing effective diameter of the take-up spool as layers of film are wound around it. You can stretch the spring if necessary to adjust the tension. It is not meant for fitting various sizes of take up spools. I think that you have to accept that the Zorki/Mir system is different to the Fed system and use the appropriate spool.

 

[arbib]

The regular looking take-up spool (like the FED 2 has, won't seat all the way in the MIR.
Q?) Does the spring loaded part on MIR adjust up/down? There is a straight slot for a screw driver to fit. (I don't want to try it until I know that is what it is for)..That would work if it is. I can lower that part a few "mm" so the back cover can close with a tske-up spool inside.

The spring is to adjust the tension on the take-up drum. It has to slip a little to accommodate the changing effective diameter of the take-up spool as layers of film are wound around it. You can stretch the spring if necessary to adjust the tension. It is not meant for fitting various sizes of take up spools. I think that you have to accept that the Zorki/Mir system is different to the Fed system and use the appropriate spool.

Thanks, Thought so...😱
Know a good source??
Seems the Ebay stores all say "Fits Fed, and Zorki camera"...😕

Fedka has known on their web site..I will email and ask anyway..

 

[arbib]

Answer on MIR take-up configuration

Answer on MIR take-up configuration

The Take up spool for the MIR "IS" different "internally" and has a larger hole in the nipple end to properly seat in the MIR.

From Fedka

Peter,
This is not only about the nipple hole size. There is also a pin inside the spool that engages with the those 4 cutouts on the MIR spindle.
I do have this spool. Most likely it will be a modern plastic spool for Zorki-4, which is also used for MIR.

Thanks for all the help
Peter