Adjusting jupiters for leicas...

[Kozhe]

Hi everybody,

I know this is not an uncommon topic, but I have seen so many different opinions that I really don´t know whether an exact focus adjustment is possible or not.

Is it really possible to adjust a regular J3 (for example) to Leica mount? If so, how? Some people say it´s just impossible, if you adjust the lens to 1m focus, it won´t focus at infinity, but I remember some people here having adjusted Jupiters... so, any first hand opinions out there??

 

[Chriscrawfordphoto]

Hi everybody,

I know this is not an uncommon topic, but I have seen so many different opinions that I really don´t know whether an exact focus adjustment is possible or not.

Is it really possible to adjust a regular J3 (for example) to Leica mount? If so, how? Some people say it´s just impossible, if you adjust the lens to 1m focus, it won´t focus at infinity, but I remember some people here having adjusted Jupiters... so, any first hand opinions out there??

Contact Brian Sweeny, he's an RFF member who does this. He did my J8 and it is accurate now up close but wont focus all the way to infinity, which he told me can't be done, but I think he said the J3 can be adjusted for close and infinity....it is more adjustable than the J-8. Email him and ask....if you're willing to send the lens to the USA he does the work and his prices are very reasonable.

 

[Uwe_Nds]

As far as I understood (and what works quite well with my J-3), you adjust the J-3 for correct focus at around 1 metre and stop down to < 2.8 for infinity.

Cheers,
Uwe

 

[40oz]

I think a better question is "do you have to?"

People have been known to send a Leica body and several Leica lenses off to Leica to be adjusted for each other. But many, many other people never give it a second's thought.

If the particular Jupiter is off somehow, then perhaps it needs adjustment. I've used a Jupiter-3 on a Leica body with no issues at all. And I'm not the only one.

 

[Kozhe]

I have a J3 which back focuses a little bit, so if I´m getting it right, I might adjust it for close ups wide open while probably loosing a bit of focus at infinity... Sounds good enough to me 🙂

 

[40oz]

I have a J3 which back focuses a little bit, so if I´m getting it right, I might adjust it for close ups wide open while probably loosing a bit of focus at infinity... Sounds good enough to me 🙂

It sounds like you J-3 is adjusted fine. It's not unusual for a fast lens to be a little off wide open at close focus. If you "fix it," it might be dead-on at close focus wide open, but it will be a little off everywhere else and the next person will wonder why their J-3 is slightly off, and put it down to FSU-Leica incompatibility 🙂

 

[Toni Nikkanen]

Is adjustment really necessary?

Is adjustment really necessary?

I got a random Jupiter-3 specimen from an auction site (not eBay this time 🙂, put on a 10 dollar M39-M-adapter, and it's focusing just fine as far as I can tell on Leica M6 and Bessa R2A. I did a close-range test at f1.5 on a target 1 meter away and it was fine. Haven't had any reason to suspect infinity might be a problem, either..

By the way, I even got the pasport with it, I remember that it had the lens specification including flange distance, maybe I'll dig it out and see what it says about that.

 

[Sonnar Brian]

Test it. If it is back-focussing a little, it needs the shim to be thickened. Typically 0.1mm will do the trick. You can use the variable stand-off ring for this adjustment. It is held in by two set screws. Undo them, unscrew the ring ~ a quarter turn, retap holes for the screws and tighten them back up. You will need to adjust the aperture ring to line-up again, three set screws hold it in.

Some J-3's will be just fine, most require ~0.1mm to be best up-close and wide-open. Stopping down to F2.8 for infinity works as the SOnnar focus shift pushes the focus back little and increases the DOF.

I optimize my J-3's for close-up and wide-open.

About 80% of the lenses I've worked on required some adjustments. Some do not, and get sent back with a "nothing to do on this one!" I do this as a hobby, and chose the J-3 as it had such a bad reputation. Check some other sites on J-3 quality, and compare with RFF's experience.

http://ziforums.com/showthread.php?t=97

http://pentax-manuals.com/repairs.htm

This is the statement that made be buy 5 J-3's to find out why the performance seemed to vary so much.

http://www.swcornell.com/camera/lenslist.html

After taking them apart, I found four required the shims to be adjusted and one had been completely misassembled. Sold all of them on RFF, no complaints from anyone about the performance after adjusting them.

 

[Santafecino]

The Russian lenses are so tantalyzing. So cheap--but do they work??? Brian Sweeney has worked on three lenses for me: a J-3, J-8, and I-61. I recently tested all three against my 50mm Summicron (recent rigid mount). All were tested wide open at 1 meter and infinity (a mountain). All were bang on at 1 meter and what I regard as acceptable (not as sharp as the Summicron, but okay for an 8x10) at infinity. I'm happy with all of them. I do a lot of color work, and most is with the J-3, and it's very nice. The Summicron does b&w.

This leaves me wondering--which adjustments change the relative positions of the elements, and which just move the entire optical unit? I would think that if you can actually change relative positions, you can change the focal length just a little bit and actually compensate for the different movement of the mount. Maybe Brian did that on some of the lenses.

My conclusion: all lenses must be compromises. A well-adjusted J-3, J-8, or I-61 is a good compromise and will not inhibit your creativity. I worry far more about flare than focus. That's another story.

 

[Sonnar Brian]

I've adjusted a couple of J-3's and one Helios-103 by moving the rear module in closer to the front to shorten the focal length, and then adjust the main shim. This does maintain focus across the range, but is tricky. It involves filing down the optics fixtures. Great way to destroy a previously working lens. It also slightly changes the rendering of the lens. You need to move the rear module in ~0.4mm closer.

You have to do this on a J-9 in lTM. The Black J-9's have a secondary shim for the rear module. It is a pain to get the rear set in correctly and then to adjust the main shim. Like a Zoom lens, that you have to adjust the cams on everytime you move it.