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Mark Wood
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 19, 2004 - 02:37 am: | 
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I have a Russian Jupiter 12 35mm/F2.8 lens in Kiev bayonet fitting (1975 vintage) with a focussing problem. The lens mounts onto the camera with no obvious problems and the focussing scale on the lens synchronises well with the rangefinder. If however, you put a ground glass screen at the film plane, it is clear that the infinity focus setting on the lens corresponds to objects at about 1.5 m being in focus! (A 50 and a 135 mm lens both seem to be fine.) Is'd be very grateful if anyone can tell me if there is a way to adjust this easily.
Strangely, I also have a 1987 Leica screw thread version of the same lens that gives a similar problem with the infinity setting actually focussing to about 3-4 m. |
Jan Dvorak
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 19, 2004 - 02:00 pm: |
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Mark:
1) Are you using a Kiev body with the Kiev lens?
2) When above lens is set to infinity, is the rangefinder focused at infinity?
3) Which Leica body are you checking the thread version on?
4) There are two pairs of rails in the film plane, only the ones close to the film opening are the actual film plane. Is that where you place your ground glass?
5) The 35mm Jupiter lens has a large protruding rear element. Is there a possibility of it being loose?
Jan |
Mark Wood
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 19, 2004 - 02:42 pm: |
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Jan:
Many thanks.
1. Yes, I've tried the lens with two different Kiev 4a bodies.
2. Yes, that seemed fine.
3. I've tried the thread version on a 1936 Leica II which is fine with all other lenses I've tried. (It was also fully serviced with a full rangefinder calibration recently.) These results came from putting a film through the camera and other lenses gave perfectly sharp pictures.
4. Yes, I used a plain ground glass screen from a Praktica VLC flush against these rails. I used the same screen recently to (successfully!) reset the focus on a Voightlander Vito B.
5. The rear element seems to be fastened in tightly.
Incidently, one of the 4a bodies also seems to focus slightly short of infinity with two different standard lenses even though the rangefinder seems OK. The other camera is fine in this respect. |
Jan Dvorak
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 19, 2004 - 03:24 pm: |
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Mark,
If the rangefinder indicates correct focus when the distance scale is set to infinity, the problem must lie with the internal focus mechanism. The lens' optical unit is obviously not sitting at a correct distance relative to the film plane.
I used to have the Jupiter 35mm in Leica mount and seem to recall that the focusing scale ring could be removed - I think it is held by three small 'grub' screws. Once removed you might find some other adjustments. I would probably start with the Leica mount lens, its mount is simpler than the Contax (Kiev) mount.
Unfortunately, the Russian quality control was spotty, specially on cameras intended for the domestic market. There are quite a few sites on the internet which deal with Russian equipment, try to do a Google search.
Good luck,
Jan |
Mark Wood
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 21, 2004 - 11:36 am: |
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Jan
Many thanks for your advice. I've spoken to a local repairer who specialises in Russian/Contax equipment and apparently, the focus is set up using thin shims inside the lens. He's having a look at the Kiev lens for me as it really is such a remarkably long way out of adjustment!
I think I've worked out where the shims should be on dismantling the Leica mount lens.
You were absolutely right, removing the focus ring (and unscrewing the rear element) allows you to remove the rest of the optics by turning the aperture ring with more pressure, after reaching its end stop. (Turn counter-clockwise and remove the optics/iris block through the front of the lens.) The shims are between this part of the optics and the focussing mount. The only shim in my lens seems to be a combination of a thin aluminium(?) ring and the "pièce de resistance," small pieces of masking tape. Real quality construction - I'm sure Leica could learn a lot from it. There's also enough grease in the focussing mount to lubricate a small car and the lens looks as if it's never been touched since it left the factory! |
Mael Bilquey
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 31, 2004 - 12:39 pm: |
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Hello.
I got the same problem on a Jupiter 12 and one of my Kiev IIIa. But I resolve it ! The lens was out of focus, with the ring set to infinity and the picture sharp for an objest about 2 meters...With these lenses the whole optic mount is screwed in the helical focusing. On my lens the rear element has been tightened too much, and what happens if you do that is the whole optic mount has been unscrewed on the opposite side. The thing you must do is to be sure the optic mount is correctly tightened when you look at the lens from the front side. (the diaphragm ring must not go beyond 1 millimeter ).
I hope my answer will contribute to fix your problem. |
