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Leica Trying to adjust a Jupiter 8 for Leica

Riego

Regular
Apr 17, 2019
19
I am trying to adjust a 1957 Jupiter 8 for Leica. I´ve created several paper shims and after adding one it has improved a lot, but still has backfocus.

Wide open and one meter after adding one shim:





I do the tests with an M7, so I have to wait for the next development ... but I think with another shim it can be fine.

Once adjusted for wide open and one meter, Will I have any focus problems at infinity and stopped down to f/5.6 or f/8?
 

BrianS

Super Moderator
Apr 3, 2013
124
It looks very close- you need "about" another 0.02mm for the shim. Focus shift is towards infinity- so stopping the lens down will give good focus at infinity. F5.6 will certainly cover it.
 

Riego

Regular
Apr 17, 2019
19
Thanks for your info Brian.

I hope my paper is 0.02mm or at least 0.01 :)
 

BrianS

Super Moderator
Apr 3, 2013
124
Paper tends to be a little thicker!

On the Jupiter-8: there is a retaining ring held in by a single set-screw, the shims rest against it. You can use this for very fine adjustment, figure 1 full turn is 0.5mm. Turn the retaining ring in small increments, ~10degrees, test and then use the set screw to hold in place at the new position. Use a sharp piece of metal for a tap for the set screw to hold in place.
 

Riego

Regular
Apr 17, 2019
19
I do not know how to thank you for so much information.

I have other Jupiter 8 that I use to learn with it and I have seen the retaining ring and set-screw.

It's easier than I thought. But I do not understand this: "Use a sharp piece of metal for a tap for the screw set to hold in place." By loosening the set-screw I can move the ring and I can tighten it in the new place. What is the sharp piece of metal necessary for?

The most complicated thing seems to be doing these tests without a Digital M. I will need months to adjust it. But it seems interesting!
 

BrianS

Super Moderator
Apr 3, 2013
124
A "TAP" is a small hole for the set screw to hold position. I have found that just tightening it may not work - the shim may lose its position. When you take the set screw out, and take the retaining ring off- you will see the tap that it screws into. After adjusting the ring, you will need to drill, or punch, a new tap for the screw.
 

Riego

Regular
Apr 17, 2019
19
New pictures with two shims:





I think I´m very close now, but I have a little back focus or a little front focus.

I need to do a new test.
 

BrianS

Super Moderator
Apr 3, 2013
124
It looks good enough to me. The error is covered by the DOF at F2, and a slight back-focus when used close-up means it will be better at infinity focus.

This is where having a Digital Leica helps- but those shots look good enough to me.
 

Riego

Regular
Apr 17, 2019
19
Thanks Brian,

I will take some pictures in the "real world".
Now I need to reindexed the aperture ring but I have some doubts about the focus ring because at minimum focus the red line is far from the M letter than in other Jupiter I have, and at Infinity does not stop at the right place either.

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Subscribe to see EXIF info for this image (if available)
 

BrianS

Super Moderator
Apr 3, 2013
124
That's typical for this age Jupiter. The near-focus is actually closer than 0.9m, so close that I've filed down the threads for the camera to follow the cam of the lens. For infinity: using the RF alone, where does the index come up for a very distant object, such as an airplane?
 

Riego

Regular
Apr 17, 2019
19
I do not worry then if it is like this in those of this age.

When I focus on something far away, it remains in the infinite symbol, but I will try something more distant like an airplane.

I'll do some tests before reindexing the opening ring. But I have some doubts here: Once the screws are removed, if I turn the ring, does not unscrew?
 

BrianS

Super Moderator
Apr 3, 2013
124
Once the set screws are loosened enough (almost removed) on the aperture ring, it will move easily and you can re-index it. This is when i tighten 1 screw to hold in place while using a sharp/pointed tool to make a "tap" for the two other screws.
 

Riego

Regular
Apr 17, 2019
19

I´ve received my new tools today and it has been very easy to reindex the ring.

Now I will do some definitive tests at different apertures and distances and if everything goes well I would like to secure the screws with nail polish.

What is the best way to apply the nail polish? With the brush? with a dropper...?
 

BrianS

Super Moderator
Apr 3, 2013
124
I use the tip of the screwdriver used for the lens- but use a broken one. A paper clip, straightened out would be a good choice. The brush is too thick, a dropper leaves too much nail polish.
 

Riego

Regular
Apr 17, 2019
19
The Jupiter that I bought from Brian is much better than this one, but I am proud of having been able to adjust one myself.

Thank you Brian for all the information!
 

BrianS

Super Moderator
Apr 3, 2013
124
KMZ maintained production of the J-8 in thread mount for the full run, and in my experience- they made the best of the lenses of the USSR. When you find one with markings in English- means they made it for export. The 1975 J-8 was made for export, and is one of the best I've used. KMZ manufactured the Jupiter-3 only until 1956. I have a Valdai J-3 and ZOMZ J-3 that match my 1956 KMZ J-3, but I went through a lot of J-3's to cherry pick them. I'm never had a bad KMZ lens. But- I did have to put a lot of work into my two 1950 KMZ J-3's, figure they were assembly practice for the new fixtures.

And- my favorite lenses are the ones that I CLA'd and/or repaired myself. Using a lens and having the focus spot-on as a result of your hard work is very gratifying.
 
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Riego

Regular
Apr 17, 2019
19
Brian, I have another black Jupiter created for export in which I will work later. It needs new lubrication because the focus ring is very loose.

In the model of the 50s I followed the instructions I found in pentax-manuals but from this model of the 70s I have not seen anything.

Do you know any manual on how to disassemble and lubricate the black Jupiter of the 70s?
 

BrianS

Super Moderator
Apr 3, 2013
124
The black Jupiter is very easy to lube and adjust; take the optics module out to reveal a slot that moves over the two stop screws for near and far positions. Unscrew the near stop screw, you can now separate the helical. Be careful to remember where the helical comes apart as there are multiple starting positions, only one is correct. Correct re-assembly is indicated by the focus showing infinity as the far stop screw stops the helical from turning.
 

Riego

Regular
Apr 17, 2019
19
Thanks Brian,

I take the optics module out and I can see the two stop pins. But, almost in my sample, are pins, so I can´t unscrew it. Maybe I need to unscrew the focus ring before?

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