Jupiter 9 focus issue HELP!

[lmd91343]

I am sure this question has been asked before. Please bear with me.

I got a 1959 Jupiter 9 (sounds like a sports car!). On my FED1, FED2, Zorki1, and Canon, the plane of focus seems to be just beyond where the RF shows focus by about 1 foot. Also, when the lens is set at infinity, the RF does not quite reach infinity. I have six other LTM lenses that work properly with the cameras.

I have set the flange distance (and checked and rechecked) at 28.80mm using a digital micrometer that is accurate to 0.01mm. I have double checked my rangefinder settings. I use a mountain peak about 10 miles away to set infinity.

I reset the RF on one of my camaras to match the J9, then it worked fine.

Is this an improperly (re)assembled J9? Is there a focus stop to adjust?

Am I stuck with it this way? Do I need to dedicate a FED2 to it?

Thanks,

[Brian Sweeney]

Kim Coxon is the expert on J-9's.

There are two sets of shims: one to set the entire lens module into the mount; and the second to adjust distance between the front and rear group.

Check out threads in the repair section; Kim has posted links to his repair guides.

[Brian Sweeney]

Kim's J-9 repair note thread.

http://www.rangefinderforum.com/foru...ad.php?t=19073

Saved you a little time.

[Kim Coxon]

If you have reset the RF and it works throughout the range, the problem is in the main shim ie the one you see when you unscrew the lens unit. The best way to fix this prblem is to use the "2 camera method".

Kim

[Mike Kovacs]

Does it not sound wrong that it focuses too long but won't reach infinity? It should focus long and go past infinity, or focus short and not make it to infinity if its a shimming issue, should it not?

[Brian Sweeney]

The lens module screws into the focus mount. So the focus mount can measure out perfectly, ie the mechanical distance from the cam to the RF pickup is fine over the focus range. The lens module screws into the focus mount and is held off by a shim. That shim must be the correct thickness for the actual focus to agree with what is indicated by the RF. That thickness can be wrong, and you can adjust the RF of the camera to compensate. If the entire range of the lens' focus is correct as per the adjusted RF, then the problem is the main shim. If the actual focus drifts off over distance, then the focal length of the lens is off and the secondary shim is suspect.

Had my second J-3 that required the mount collar to be polished down; it would not reach infinity and the helical was screwed all the way into the mount. Polished it down a little, screwed the helical in farther, got it to infinity. The lens could not have focussed correctly unless the camera had been adjusted for it, and it alone.

[lmd91343]

Kin, Brian,


Thank you for your quick response. Kim that is a good site. Good info there. I've read thru your J9 instructions.

The lens would be perfect if the RF cam were just a 1 or 2mm longer. I'm tempted to epoxy brass shim stock

I don't see where in your instructions that I need to augment the shim. Is there a way to measure how much shim to add? What type of material do I use. How do I cut it in circles?

Thank you,
Lance

[Kim Coxon]

Lance,
Read Brian's post again. First off, I am getting a little confused by the exact nature of the problem.

First: Put the lens on a known good body. Set the lens to infinity. Does the RF patch show infinity? If yes the cam is OK. If not someone has put the focus unit together in the wrong way. The are a very large nubers of combinations and only one is right. See my instructions for the way to do it.

Second: Now the camming is right. Focus at infinity and check that the image is correct using a piece of ground glass and either an SLR or a lupe. If this is wrong the main shim is out.

Third: Repeat step 2 at close focus. If the focus is out here but was good at infinity, the secondary shim is out and the focal lentgh needs adjusting. Once this is done the main shim will need adjusting too.

Kim

Originally Posted by lmd91343

Kin, Brian,


Thank you for your quick response. Kim that is a good site. Good info there. I've read thru your J9 instructions.

The lens would be perfect if the RF cam were just a 1 or 2mm longer. I'm tempted to epoxy brass shim stock

I don't see where in your instructions that I need to augment the shim. Is there a way to measure how much shim to add? What type of material do I use. How do I cut it in circles?

Thank you,
Lance

[ZorkiKat]

Kim

the type of grease used seems to be relevant to the J-9's focus movement accuracy. Many of the J-9 which I got which did not focus correctly all seemed to have been regreased. They moved smoothly alright, but the movements were not precise enough for correct focusing. Having new lubrication makes the lens suspect of being incorrectly reassembled, but in some of the J-9 I repaired, replacing the 'new' light grease with denser lubricants made the lenses work right. It seems that the J-9 helixes need the thick heavy grease (which makes many of these lenses turn more heavily than other lenses, or even other J9 in non-LTM barrels) to dampen their movement to engage more accurately.

Jay

[rover]

Hey Kim, if a J9 showed up at your door, I don't know, just dropped off by a stork or something, how much would it run me get is shipped to my door step all well adjusted and cleaned and stuff?

We have Brian in the J3 trade, now we need a J9 source.

[Kim Coxon]

At the moment, I can't take any more and probably not for at least a couple of months. I am still trying to catch up on the jobs I have neglected for people over the last few weeks. Although Linda is now mobile, I am still short of time.

Kim

Originally Posted by rover

Hey Kim, if a J9 showed up at your door, I don't know, just dropped off by a stork or something, how much would it run me get is shipped to my door step all well adjusted and cleaned and stuff?

We have Brian in the J3 trade, now we need a J9 source.

[lmd91343]

Hi Kim,

When I put the lens on a good body, scale focusing is accurate. With the lens set at infinity and a subject at infinity, the subject is in focus. With the lens set at two meters and the subject at two meters, the subject is in focus.

When I put the lens on a properly adjusted RF (works with 6 other lenses), with the lens set at infinity, the RF patch is short of infinity. When focusing at shorter distances, the plane of focus is just beyond where the RF patch shows. If an object at a distance of four feet is in RF focus, an object at five feet will be in be in focus on the film plane. The object in film plane focus is one foot (variable) further away than the RF focus shows.

If I adjust the RF on the camera to match the lens, it seems to work fine.

I am sorry for any confusion.

Thank you,
Lance

Originally Posted by Kim Coxon

Lance,
Read Brian's post again. First off, I am getting a little confused by the exact nature of the problem.

First: Put the lens on a known good body. Set the lens to infinity. Does the RF patch show infinity? If yes the cam is OK. If not someone has put the focus unit together in the wrong way. The are a very large nubers of combinations and only one is right. See my instructions for the way to do it.

Second: Now the camming is right. Focus at infinity and check that the image is correct using a piece of ground glass and either an SLR or a lupe. If this is wrong the main shim is out.

Third: Repeat step 2 at close focus. If the focus is out here but was good at infinity, the secondary shim is out and the focal lentgh needs adjusting. Once this is done the main shim will need adjusting too.

Kim

[Kim Coxon]

In that case, it looks very much as though someone has re-lubed the len and put it back together incorrectly. As I said in my repair article the secret is the extra half turn when inserting the RF tube. Without this extra half turn the RF ring sits too far forward.

Kim

[lmd91343]

Kim,

Thank you. Now I have another rainy day project to add to the list!

Would high temperature waterproof teflon grease be ok?

Thanks again,
Lance

Originally Posted by Kim Coxon

In that case, it looks very much as though someone has re-lubed the len and put it back together incorrectly. As I said in my repair article the secret is the extra half turn when inserting the RF tube. Without this extra half turn the RF ring sits too far forward.

Kim

[lmd91343]

Help! Please!

I am still having problems. Following Kim's excellent instructions, I have disassembled, cleaned and reassembled the lens mount. I have reassembled it about a dozen times. I have used the two camera method for collimation.

Using my micrometer and my Canon 7 as tools, I have a lens that focuses at infinity, and the RF patch coincides there (infinity is a mountain top about 9 miles away for me).

At distances of six or less meters, the focus plane is about one to two inches different by comparing the RF patch to the image on the focal plane (Scotch tape with the shutter on T).

Is this the best I can expect? What else can I do? Is this the error that Dante Stella has written about?

Thank you,
Lance

[lmd91343]

Using Kim's and Fedka's wonderful write-ups, I have been able to fix my lens!

The key for me was measuring the throw of the RF cam from 7.52mm above the lens seat at infinity to 4.79 at 1.15M. I measured several lenses to get these values. Fedka has a typo and lists the offset for 1.15M as 5.8mm.

My lens cam at infinity, after going thru about 20+ re-assemblies was 8.06, 7.42, or 4.??. The problem was the lens focus stop pin. When I removed it, using Kim's method, I was able to get 7.52/7.54mm at infinity. I did not drill and tap a hole at the new infinity stop, so the lens will focus slightly past infinity. I also had to reset the focus scale ring to match the new infinity, dilling new holes for grub screws.

I collimated the lens using a 400/4.5 lens with the two camera method. With a 55mm it looked pretty good without collimation. With the 400, collimation was much easier.

This is a nice lens. It is sharp where focused. The OOF is nice. I think I'll like this for portraits better than my Canon SLR 85s.