bad focusing Jupiter-12, need help

fer_fdi

fer_fdi

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Hi all,

I recently acquired a 1956 KMZ Jupiter-12 that draws very nicely but it can't focus properly. It consistently focus closer to camera than intended.
At 1 meter the error is about 25 cm, at 5 meters the error is about 3 meter. Obviously it can't reach infinity as shown in one of the images.

I need help to solve this problem, repair it... maybe it has some shims inside?
Can I have any hope?

I love how this lens draws so I'd like to try to solve it myself
Sending it for repair to someone within Europe is an alternative but I'm short in funds.

Here you can find some example photographs where intended focus point is marked;
you'll see focus is always closer to camera:

https://goo.gl/photos/gqfjcmznnbDcWb6T9

Many thanks in advance
 

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fer_fdi said:
I'm using a CLE and a good (not chinese noname) M adapter.
The focus error is large.

My other Jupiter-12 (LZOS 1986) focus spot-on with any adapter, including chinese noname ones.
Click to expand...

I was going to recommend that you ditch the lens you have for a more recent version of the Jupiter 12. I have a 1988 vintage and it is very good on my IIIf.

Of course you know that the register with Leica mount differs, but the errors you are describing are so severe that the copy you have probably would be out of focus even on a Russian made camera.

Where did you buy it? Sometimes these lenses are taken apart and put back together improperly and then sold. After that they keep coming up like a bad penny.
 
This fellow had a similar problem with an LTM J-12 :


"One more irritant I had - my helicals were, I thought, reassembled properly. My lens would only focus to 1.2m rather than 1.0m. Turns out after much fiddling, it was right! If your lens does this, remove the aperture selector captive screw, unscrew the aperture selector by one turn (making sure the dot is opposite the aperture numbers), reinstall the screw, then screw the aperture mechanism back into the barrel. What was happening was with the aperture selector screwed all the way in, it was bottoming-out in the lens barrel before hitting 1.0m."



http://web.archive.org/web/20060117...stuff.com/forum/read.php?f=21&i=35746&t=35735
 
traveler_101 said:
I was going to recommend that you ditch the lens you have for a more recent version of the Jupiter 12. I have a 1988 vintage and it is very good on my IIIf.

Of course you know that the register with Leica mount differs, but the errors you are describing are so severe that the copy you have probably would be out of focus even on a Russian made camera.

Where did you buy it? Sometimes these lenses are taken apart and put back together improperly and then sold. After that they keep coming up like a bad penny.
Click to expand...

This lens draws in a very special way to my eyes.
I'll try to open it and see if there are shims inside.
It draws different than my LZOS specimen
 
xayraa33 said:
This fellow had a similar problem with an LTM J-12 :


"One more irritant I had - my helicals were, I thought, reassembled properly. My lens would only focus to 1.2m rather than 1.0m. Turns out after much fiddling, it was right! If your lens does this, remove the aperture selector captive screw, unscrew the aperture selector by one turn (making sure the dot is opposite the aperture numbers), reinstall the screw, then screw the aperture mechanism back into the barrel. What was happening was with the aperture selector screwed all the way in, it was bottoming-out in the lens barrel before hitting 1.0m."



http://web.archive.org/web/20060117...stuff.com/forum/read.php?f=21&i=35746&t=35735
Click to expand...

thank you, although my problem seems the opposite, It's good info

a well known wise man told me to look for shims inside. Let's see if I can open the lens without screwing it further... :S


I need detailed directions about ho wto dismantle the lens to find the shims

.
 
The non-50mm RF lenses have a multiple helical in them: one to move the lens forward and back for focusing, and another to move the RF coupling cam at a different rate (the cam has to move at the rate that a 50mm lens would move, because that's what the RF is calibrated for). If the lens has been completely taken apart for service, it can be very fussy to get the RF coupling helical started in the right place. If it's off, the RF cam will be either too far back or too far forward and so will not operate the RF correctly. Sometimes a repairer will not notice, or else get tired of messing with it and sell the lens. I have a Jupiter-9 85/2 that had this problem. Luckily in my case, the cam was 1/2mm too far back, and I could grind it back to the correct position without taking it all apart .... but on a 35mm, I think this would be impossible to do safely. My guess is that it's assembled wrong and needs to be taken apart and put back together correctly for the RF to read correct.
 
thank you Rick. If that's the case I can not do it myself... : (

in case I need to send it for adjust, any tech recommendation in Europe that it is not expensive?
 
traveler_101 said:
Snip! ... Sometimes these lenses are taken apart and put back together improperly and then sold. After that they keep coming up like a bad penny.
Click to expand...

Hi,

I'll second that and add that the people who made the lens always get the blame for it despite all the blatant evidence of people messing around with things they don't understand...

A register of the sellers and serial numbers of the lenses is what's needed.

Regards, David
 
from my experience and what I see and read, black ones have no problems usually

but yes there's always the risk that someone opened the lens and reassembled the wrong way and that is very annoying.
Sometimes they have shims to match one specific camera and it is a matter of extracting them.

My second J-12, KMZ from 1956, has one or both problems but draws very nicely.

Can anyone recommend a tech in Europe to collimate the lens? I'm in Spain
 
I removed the shim inside the lens (very easy btw, thanks B.) now is a bit better but still no good focusing.
A pity because I love how this lens draw.

Is there anything else I can look at?

Any recommended tech in Europe to adjust this lens? I'm in Spain, the closest the better.
 
Yes, there's my note above, but it's not a whole lot of fun.
 
thank's Rick. I meant something I could look at/do myself.

If it needs to be reassembled correctly it will have to be sent to someone.

A very experienced, kind and helpful gentleman was giving me help and guidance to open the lens and look for the shim. In his opinion, looking at the pictures I linked, it does not look like a mismatch on the helicoid due to improper reassembling, since that would produce a much noticeable focusing error (like focusing at 2 meter when in infinity position) but...

I may have to send it for adjustment : (
 
I would check to see if Oleg is back in business.
He suffered a bad fire at his home/shop in Russia earlier this year.
I would, and have, trust Oleg with any of my cameras and lenses.
Contact him at: http://www.okvintagecamera.com/
I've dealt with Oleg for more than 10 -years.

I'm the other old Rick on this list. (The older one, not the smarter one.) and a devoted J-12 fan.
I have one each in ltm and in Contax/Kiev mount. Love 'em!
 
Last edited:
Fer,

It is nice to see you again. We exchanged a few messages in Flickr with regards to your Jupiter-12.
It is unfortunate that you had it not fixed yet.

My KMZ 1956 Jupiter-12 would front focus badly, with no infinity focus.
I had it fixed by a local Leica repair shop, but paid almost what I had spent on the lens itself.
Maybe you'd better buy a newer lens.
 
Hi Celso! Well I have yet to shot the last tests and then decide.
Someone is helping me diagnose the lens.
I like how this specific lens draws (it is both sharp and sweet) so I may try to repair it in UK if costs are fine.
After the tests I'll decide.
Thanks for your support : )
 
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