Weird jupiter 8

I

ijesato

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I´ve received today a jupiter-8 from ukranie(bought on eBay) and it has some problems that I don´t know if I can fix or if the lens is completely useless.

-First: when I thread it on the camera (a Bessa R) the DoF scale does not stays on top, it stops on the right-down side (around 4 or 5 in a clock).

-Second: the aperture dot is way off the aperture numbers.

-Third: the focusing barrel is somehow not parallel to the rest of the lens.

Thanks for your knowledge and sorry for my english (my first language is the spanish)
 
Probably some kind of amateur repair job.There should be a diy repair manual somewhere in the Forums. What do you mean by the focusing barrel is not parallel?
 
the third problem is fixed, I loosen the 3 screws on the focusing barrel and put it on its place. The problem was that une side of the barrel was closer to the body than the other, so when you turned it seemed to "wooble"

the other 2 I don´t know how to fix them.
 
Have a here for the Jupiter 8 re-lube instructions, which will tell you how the lens comes apart:

www.pentax-manuals.com

You don't actually need to take apart but on most of the J-8 models (not all) it's possible to move the scales around to the correct place. You may find you have to live with them all not at 12 O'clock though.
 
Thank you all, I think I will mark another dot for the aperture scale and try to move the DoF scale if possible

when I discver if the lens is in good optical condition maybe cuold be pissible to forgive her the little flaws.
 
ijesato said:
Thank you all, I think I will mark another dot for the aperture scale and try to move the DoF scale if possible

when I discver if the lens is in good optical condition maybe cuold be pissible to forgive her the little flaws.
Click to expand...

I have a J-3 that had the same problems. The previous owners/repairman were obviously having fun with the lens since there are engraved secret code under the barrel mantle; there is more than one hole to place the focus restrict bolt; and so on.

When I got the lens the DOF markings were upside down and the aperture marks were correct. However the focus was off by half a light year (not caused/curable by shimming), so I had to tear everything down, adjust and reassemble.

In the end the focus is spot on, for, eh, "Russian leica screw mount standard", and the DOF marks are near 12 o'clock but the aperture marks were at 9 o'clock position. I just choose to live with it.
 
If the aperture dot is off, the front element has been screwed in too far or too little. Don't make a new one.

Not having the distance mark line up at 12 o'clock is fairly normal on LTM lenses. The apparent idea was to see the distance despite having an accessory finder mounted.

D
 
I know that if you screw the front element too far changes the position of the dot but there is no way to leave the front element where it should be without leaving it loose. Or is it possible?
 
It's only possible by adding a shim to the one behind the optical block. If you were using the lens on a digital camera this would be ok, you'd be focussing via the live image. For use on a film RF you would have upset the working distance, however and your RF would no longer give correct focus. Better to move the scale, assuming you know the lens focusses correctly at present. What would concern me is that the dot would have lined up properly when the lens was shimmed originally, which implies the shim has been altered since.
 
Hi,

The focusing scale mis-alignment is not unusual. Most of my old Leicas suffer from it. If the focusing is OK (tested on a film) then I would forget about it. I guess the scale moves slowly round as the lens is used.

Minor adjustments to lens like this do not cost a lot and that is what I'd advise. You should be pleasantly surprised at the difference it will make.

Regards, David
 
Today I´ll receive a test roll of film that shot to see if its in focus or needs shimming and maybe if needs it, that fixes the missalignment
 
Hi,

I will wish you good luck; I expect a lot of other people all around the world are wishing it as well...

Regards, David
 
I´ve received the pictures from the lab and I sincerelly say that I am pretty impressed with the results.

The lens is very sharp, has an out of focus incredible, very contrasty and beautiful colors.

There is something bad (it couldn´t be perfect), it focuses a little bit further away that where it should. Whay have to do? add or quit shims?

Thank you all for your help! :D
 
If the actual focus point is behind where the RF/scale indicates, you'd need to add thickness to the shim(s). Before you go messing with things like that though, do make quite sure the RF is correctly set and not in need of adjustment. How far off was the focus?
 
That's a pretty small error, I'd think twice about messing around for that unless it really matters to you. You'd be talking a very thin shim. As above, check the RF calibration first anyway.
 
It's trivial to shim a Jupiter 8 so why not give it a try. If your Jupiter 8 is built the same as lynnb's Jupiter 8 (which I very recently CLA'd) you can unscrew the entire optical cell from the barrel by grabbing each end of the lens and twisting anti-clockwise. There's a shim (possibly two shims) that sits between the barrel and the optical cell to correctly position the optical cell in relation to the film plane, and all you need to do is make that shim slightly thicker. A layer of cellophane tape added to one side of the shim should do the trick. Just trim off the excess, and see how you go with that. You won't need to add much extra thickness (perhaps only 0.05 mm or so) to the existing shim(s) to fix the back focusing.

24575898401_1346bf64ca_b.jpg
 
thanks to both, I´ll try the cellophane tape and test it again

How do I test the RF callibration?

(sorry if I ask too much, but its my first rangefinder and I am a bit lost)
 
Have a look in the stickies for a thread on how to adjust your RF. To check it out you'll need two targets, one at "infinity" and one at 1 metre. The ideal one for infinity is the moon or a star but something like a very distant building (tower or the like) is fine as long as it really is some distance away. The RF should agree with the actual distances at both ends of the scale. For the 1m target, measure from the film plane not the front of the lens.
 
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