Collimating Jupiter-8 on Zorki 1

[Bradd Cluckey]

I picked up a Jupiter-8 at a local used camera shop. I'm glad to have a 50mm slightly faster than my I-22, but in testing the lens out, I found that when shooting wide open and up close, the area in focus is about ten inches closer to me than the point of focus indicated by the rangefinder. I understand that I will need to adjust the shims to fix this, but I am a little shakey on how to proceed.

I've read about collimating using two cameras, but my one and only LTM body is a Zorki 1 with a non removable back, making it impossible to see a focusing target placed on the film plane (required for this method of collimation afaik). Is there a way to check my adjustments using the two camera method on this body?

Also, a few questions for those who regularly adjust lenses. Should I add or subtract shims to adjust focus in the direction I need (ten inches farther away)? What would be a ballpark figure for the amount of adjustment? .2mm? .5? More? Less?

My plan as of now should work, but may be a very slow process. To avoid wasting film what I think I'll do is use the last frame or two of each roll I run through as tests for this lens. Add a shim, test the lens, develop, inspect, repeat. This would be slow as lately it takes me a day or two to shoot a roll. I'm hoping someone knows of a better way for me. Would I be better off just devoting a roll to the test and adding a shim each frame (making note of the number of shims used each frame) determining the propper number from the results, then adjusting as needed?

Also, why do I think of these things at 4:00am on a monday morning instead of sleeping? 😉

I hope some of that made sense, and I'm very sorry for the long post, I'm still young in the world. I promise someday I'll help answer questions rather than continually asking them.

Goodnight and thanks to anyone who even reads all the way through this silly and jumbled post.

Cheers,
Cluckey.

 

[Sonnar Brian]

If the lens is focussing 10inches to close at the minimum shooting distance of ~3ft, the shim is much too thick. Start with 0.5mm. Unscrew the optics module from the focus mount, there might be a stack of shims in it. Try removing one. Once it is corrected, you need to reset the aperture ring. Take out set screws, turn the aperture, tap new holes, put back in.

 

[Valkir1987]

I maybe mistaken, but the rangefinder of your camera has to be adjusted for close focus in the first place. Your lens and mount is shimmed for infinity, and shimming the lens will probably not give the correct result if the rangefinder is not correctly adjusted.
The rangefinder cam that touches the lens and moves forward and backward can be turned as well. Zorkikat has a good manual for this: http://jay.fedka.com/index_files/Page422.htm\

 

[Bradd Cluckey]

Thank you Brian, I'd have added shims...that would not have worked....

And thank you Valkir, but I've already adjusted my rangefinder at close focus and infinity, and it is spot on with my other lens (an I-22)

Cheers,
Cluckey.

 

[.Lucifuge.]

And thank you Valkir, but I've already adjusted my rangefinder at close focus and infinity, and it is spot on with my other lens (an I-22)

Well, Brad the trick with FSU RF is that, U have to adjust the RF every time U screw in different lenses. It's Zorki not a Leica.

Greets😎

 

[Sonnar Brian]

Well- I've NOT had to adjust the RF of the Camera for the lenses on my Zorki 3M's... But most of the FSU LTM lenses that I've used did need adjusting. Contax/Kiev mount lenses as well. Once shimmed, they do quite well on any of the cameras.

 

[reagan]

Well, Brad the trick with FSU RF is that, U have to adjust the RF every time U screw in different lenses. It's Zorki not a Leica.

This is news to me.

 

[wolves3012]

Well, Brad the trick with FSU RF is that, U have to adjust the RF every time U screw in different lenses. It's Zorki not a Leica.

Greets😎

I've noticed minor differences between lenses but it's never been enough to make adjustments to the RF necessary.

 

[Bradd Cluckey]

Update: Got it, thank you so much everyone. This is good enough for me.

Crappy scan of one hour print. But you get the idea.

So thanks a million.

Cheers,
Cluckey.

 

[momus1]

Very nice shot. Focus looks spot on too.

 

[Sonnar Brian]

Very nice shot-

Okay, but you have to tell us what you did to fix it!!!

It will help others with the same problem.

 

[Bradd Cluckey]

Of course, how inconsiderate of me.

Upon determining that the removal of shims was in order (on Brian's advice seen above) I set about the trial and error process.

First, to establish a baseline I removed the optical block and checked the shims, and to my surprise there was only one. I measured it with a micrometer (it was a little less than 0.5mm), and cut another shim from a book cover that was half the width of the metal shim that came with the lens.

For a test target I arranged 3 objects about 6 inches apart on a coffee table in good light. I focused on the center object in each test.

On to the testing. I decided to shoot four exposures or so at each stage of the test (all wide open and at approximately one meter). After each stage I shut myself in the bathroom, plugged up the light leaks around the door, turned out the lights. I pulled out and snipped off what seemed like the appropriate amount of film from the casette of the test roll (10 inches or so). I developed the strip by simply dunking it up and down in a plastic cup of developer for a few minutes and then in cups of water and fixer (hindsight being what it is I should have been wearing gloves, I had quite a skin reaction on my left hand index finger) and inspected the negative with a loupe to evaluate the area in focus. After each stage I cut another leader and continued using the same roll (waste not want not).

The first group of frames was with the original amount of shimming to verify that it was indeed focusing too close. It was.

I replaced the metal shim with the half width paper shim and shot four more frames, upon developing the focus was nearer to the center target, but still a few inches closer than intended.

The third time, I went totally shimless, expecting the lens to focus too far back and that I'd need to cut some thinner shims, but as it turned out (luckily for me) this was just right. The center object was in sharp focus.

I loosened the three set screws and realigned the aperture adjustment ring (as explained above by Brian) and went to bed.

The next day I ran a test roll through to be sure and was again satisfied by the results.

Whether or not this is the best method for adjusting a lens is debatable, but it worked for me.

I hope this helps anyone wishing to finetune their J-8.

Cheers,
Cluckey.

 

[Sonnar Brian]

Thankyou- and testing with film is the best possible solution for accurate focus. Film is not perfectly flat in a camera. Using ground glass often means applying a "fudge factor" either before using the lens, or after getting the results back from the first roll of film.