Jupiter-12 - Unsharp at any distance

[Brambling]

The mark I used was probably 1/3 from the center as this ground glass has a split image and a microraster in the center. When I focus a rangefinder I use the edge of the patch to focus, but the size of the patch varies from camera to camera. I really do not understand what's the issue with this lens. I've used the Kiev 4 after the above shot were made, with a different lens and with excellent results.

that's what I meant, forgive me for my bad English

 

[Brambling]

The mark I used was probably 1/3 from the center as this ground glass has a split image and a microraster in the center. When I focus a rangefinder I use the edge of the patch to focus, but the size of the patch varies from camera to camera. I really do not understand what's the issue with this lens. I've used the Kiev 4 after the above shot were made, with a different lens and with excellent results.

There is also the possibility of a non-original rear component - they often fail, are often very scratched, and they can easily be replaced with similar technical lenses from Jupiter 12, only without the helicoids that were in devices for copying drawings or in devices for reading microfilms in libraries , there were quite a lot of them.
But in any case, sufficient sharpness for shooting can be achieved by adjustment, which is probably what you did by disassembling and assembling this lens.
Worth checking?)

 

[Brambling]

My Jupiter 12 KMZ M39 1952 gave me a very strong round glare, especially on color film, the glare from behind the belt at the back.
I had to transfer lenses from Contax/Kyiv 1973 to the M39 body, everything went quite well, after adjustment this lens became quite sharp.

 

[Kai-san]

Not many options left, so I will shoot a test roll to see if things have changed.

 

[Kai-san]

It seems the age of miracles has not passed yet. I shot a roll of Fomapan 400 this afternoon with both shims in place, see two of the shots below. Nothing of what I have done with this lens can explain it, but here we are. Thanks to all for your support! 🙂

 

[dxq.canada]

My guess ... you took apart lens ... noted it was very tight ... put it back together ... not as tight ... so focal plane distance has been extended.

 

[Brambling]

I’m very happy for you and for your lens.I, too, always expect a miracle.But still, I suspect that perhaps the rear lens block was simply not fully screwed in and was slowing down due to, for example, a scuff on the thread, and you corrected it.But this is also a miracle - and you did it!
😉

 

[dexdog]

Congratulations on the fixed lens, looks good!

 

[Sonnar Brian]

Sounds like an element was loose- and taking apart and re-assembling fixed it.

"Just in Case"- with the lens off the camera, give it a little shake to make sure all is tight internally.

 

[Kai-san]

It often helps to sleep on a problem. I realize that if I had used the collimation method before I took the lens apart, I would have seen what the problem was. That is; if I had known what to look for, and now I do. What I learnt was that if there is too little shimming you can get the collimation mark in focus by moving the focus away from infinity on the camera you use for collimation, the Nikon F3 in this case. If there is too much shimming you cannot get the collimation mark in focus. I had to use a lot of force to loosen the rear group, and the front group was so tight that the aperture selector came out with it. From experience I always assemble things with a firm force, but never excessive. So when I assembled the lens I used less force than what was used in the previous assembly process. This would have increased the shimming effect and brought the lens into correct focus. I did not realize how little it takes to get a lens out of focus, that was what confused me. I have shaken the lens, nothing loose.
So thanks again to you all!

 

[titrisol]

Today I rigged up the collimation set-up, I put the J12 on a Kiev 4; same camera that produced the shots above. I used a ground glass with a mark on the ground surface and made sure the ground surface was facing the lens. Surprise, surprise, with both rings in place the focus is absolutely perfect! With only the thickest ring in place I had to shift the focus on the 135mm Nikkor to halfway between infinity and 20m, with only the thinnest ring in place much worse.
Then I put the J12 on a Contax II with both rings in place, ever so slightly out of focus as if it could have done with perhaps 0,1mm extra shims.
I also tried the method TenEleven suggested, it looks OK though I found it a bit difficult to execute.
I think I need to shoot a test roll with the thinnest ring removed to see what happens.

So you are saying that the Kiev and Contax II have a slight difference in the flange distance?
Does this also happen with other lenses?

 

[TenEleven]

So you are saying that the Kiev and Contax II have a slight difference in the flange distance?
Does this also happen with other lenses?

I obviously can't speak for Kai-san, but nominally the flange distance of the Contax II and Kiev should be identical.
Ultimately of course both are old cameras with a likely history of varying quality of repairs and perhaps alterations and different degrees of quality of manufacture.

 

[titrisol]

I obviously can't speak for Kai-san, but nominally the flange distance of the Contax II and Kiev should be identical.
Ultimately of course both are old cameras with a likely history of varying quality of repairs and perhaps alterations and different degrees of quality of manufacture.

The J12 goes in the extrnal mount of the Contax/Kiev. ~0.1mm deviation according to Kai-San is possible after decades and who knows hoe many hands/technicians

 

[santino]

So you are saying that the Kiev and Contax II have a slight difference in the flange distance?
Does this also happen with other lenses?

An early Kiev is not a Contax II copy, in fact it is a Contax II. There maybe qc issues but the flange distance is the same.

 

[Kai-san]

So you are saying that the Kiev and Contax II have a slight difference in the flange distance?
Does this also happen with other lenses?

No, I just stated what I saw from the collimation. I tried to set up the collimation as accurate as possible with the means I had available, but when I was about to mount the Contax II on the tripod I discovered that the tripod screw on this camera is fixed to the camera back and not the camera body. So I had to balance the Contax on the tripod plate, and that could have been the cause of this tiny difference. I have used the Zeiss Sonnar 1.5/50 and the Jupiter-3 on both cameras without seeing any difference, and I am not going to check it with a microscope. I have not tested the J12 on the Contax II yet, but I will.

 

[Kai-san]

Yesterday I tested the J12 on my Contax II, can't see anything wrong with it besides the morning haze.

 

[dxq.canada]

You fixed it trying to fix it !!!