Ever had an off-focus Jupiter-12 in Kiev mount?

[darkkavenger]

Hello!

Today I picked up a couple rolls of film & developed photos at my lab.

I noticed that all my photos shot with a 1958 Arsenal-made Jupiter-12 Kiev mount were off focus. I loaded some on a gallery, you can see them here : http://www.rangefinderforum.com/photopost/showgallery.php?cat=6110

The photos with green squares are those shot with the J-12, the green area marks the area where I remember having been focusing. All the photos were taken on the same Kodak Tri-X 400 film. You can notice the difference between how the J-12 performs, compared with the Sonnar or Jupiter-3 photos.

Anyone has ever seen this ? And does anyone has a clue of what has gone wrong ?


Thank you!
Max

 

[darkkavenger]

wow i'm going to have to invest, I guess ? 😉

 

[darkkavenger]

I guess I can use the focusing screen of my pentacon six, then ? 🙂

 

[peterc]

I had one this happened to. the set screw that holds the lens assembly in the lens barrel had come loose and the lens block was moving in the barrel. You could screw it out of the barrel by turning the aperture ring. Screwing the lens block back in again and tightening the set screw cured things.

Peter

 

[OldNick]

I agree with Daniel. I have a J-12 in LTM that is a little off at close distances, but nothing like you demonstrate. If you can check it with a ground glass, it might offer a clue. Most of the recent airplane shots in my gallery were taken with my Leica IIIf and Jupiter 12, and they are very sharp.

Jim N.

 

[darkkavenger]

I must say that I'm not used to such a behavior, when all my other lenses in various focals have given me outstanding results. Thanks all for the suggestions, I will try as soon as I can.

 

[doubs43]

I have one in Kiev mount that was out of focus. The cure for mine was to unscrew the rear lens element until it was in-focus on ground glass at the film plane at infinity and then make a washer of the correct thickness to fit under the rear element when it was screwed tightly in place, keeping the correct focus.

Depth of field, even at f/2.8 is enough that a few thousands of an inch isn't critical so your washer or shim material can be a little off in thickness and still be fine. Or, you can start thicker than needed and reduce the thickness until you have it exactly right.

Walker

 

[darkkavenger]

Nice perspectives for this weekend ! Thanks Walker

 

[rolleistef]

max,
have you checked the RF itself?
you shouldgo on this site and download the focus testing target.
Otherwise it seems back focus is quite common place on this kind of lens... the older they are the more reliable they seem don't they?

 

[Mark Wood]

I had what looks like the same problem with a Jupiter 12 in M39 mount. It was actually focussing "beyond infinity" at the infinity setting and even at f11, the depth of field wasn't enough to bring distant objects into focus. I solved the problem by removing the rear element and then the other ("front") block of optics out of the focussing mount. Concentrating on the front optic block, removing a set screw allows you to vary the separation of the two parts via a screw thread. I increased this separation by one turn on the thread, and reassembled the lens and it now appears to be fine.

 

[jonasv]

A Holgiter-12, quick, someone sell this to the Lomo factories!

 

[darkkavenger]

Hi Stéphane, what do you mean by "checking the RF" ? (maybe you can tell me in french via PM it'll be easier for both of us). The link you pointed me to isn't working for me alas.

If you check on the gallery to where I point (see my first post), the camera behaves perfectly with other lenses.

Regards!
Max

 

[darkkavenger]

Mark : I think I'll avoid disassembling my J-12! I'm not really a "manual" person, I'm better at repairing computers than lenses 😉

 

[varjag]

Max, my 1986 black J-12 came defocused out of factory. The shim inside was *way* too thick, rendering lens unusable at f/5.6 and wider. I replaced the factory shim with several thinner paper shims, and it is now more or less on the spot.

I used Mike Elek's method to collimate the lens (where you use an SLR with tele lens).

 

[darkkavenger]

Thanks for the feedback, Eugene, I'll check when I get home tonight (waaaay late)!

 

[darkkavenger]

ack... I don't have any 35mm slr alas 🙁

 

[Bob L]

Hi Max
I had the same problem with one of my J12 and had to do the same job with the rear element as doubs43 did with his lens, now it 's tack sharp and the whole job was done in a couple of minutes.

 

[darkkavenger]

where can i find such a ground glass ? maybe buying a cheap old slr ?

 

[comp_wiz101]

Have a small piece of glass cut at either a glass cutter shop, or even a photo framing place. Then, cover it in one layer of that kind of smoky translucent packing tape, what we call "scotch" tape over here. Sorry, I have no idea if it has the same brand name over there!

Here's a link, to actually see what the heck I'm talking about: Scotch tape picture

 

[darkkavenger]

Ok folks, I figured out that the lens is easily dissassembling itself without a screwer... how weird is this. The rear element unscrews without trouble, and the front element, when turning the fstop ring, also unscrews itself easily without having to push. Maybe this lens has been disassembled already. It seems that i'm going to have to stick on 50mm's for some time. I feel pretty dumb at doing anything as you guys describe, but I'll be trying. Thanks for all the help!