Focus Problems with Jupiter-8 and Industar 61 on Zeiss ZM: lens or adapter?

[capito]

Hi everybody -

shot a test roll with a Jupiter 8 this weekend (my first shots with a L-Mount rangefinder) and didn't think much until I noticed that I could focus way, way over infinity.
I checked the adapter and noticed that the red line for focus didn't line up properly, as you can see in the pic. To get things in infinity lined up in the rangefinder, I have to focus to around 3,75m. Hmmm....

Now I'm asking myself if this is because of the adapter or if its problems with the lens itself. That the lens isn't lined up properly must be because of the adapter. It's a pretty cheap one, maybe I made a mistake in getting it.
But focusing to 3,75m for infinity makes me think that something is really wrong with the lens. Or am I mistaken and this is also a symptom of a bad adapter?

- Chris

 

[Sonnar Brian]

The helical is probably misassembled. Someone took the lens apart, and did not start the helical on the correct thread when screwing back together. You need to take the optics module out, take out the stop screw visible through the hole, and screw it back together so that infinity and the RF agree.

This thread shows the pieces of the focus mount.

http://www.rangefinderforum.com/forums/showthread.php?t=93825

 

[capito]

You need to take the optics module out, take out the stop screw visible through the hole, and screw it back together so that infinity and the RF agree.

Ughhh... I dreaded hearing that.:bang:

But for the price I paid I won't feel that upset if the experiment goes wrong.

 

[Kim Coxon]

Hi,
You can also get full instructions on servicing the J8 here on my website.

http://pentax-manuals.com/temp/j9/image1s.jpg

If you get stuck drop me a pm and I will try and help. I am in the UK. By coincidence, I have just sent a slightly different version back to the owner in Austria.

Kim

 

[capito]

Just received a Industar 26 and it's got exactly the same problems!
The lens doesn't line up and isn't flush with the adapter. I can focus past infinity, and if I line up something in infinity, the scale is at around 3,5m.
I'm not sure at this point if I sould try a different adapter or if I should take the lenses apart and attempt putting them together correctly.

 

[capito]

I hate to bump this thread, but I just tried out another Jupiter 8 and it's exactly the same.

So now I'm really wondering if I've got three lenses which all were so badly reassembled, or a bad adapter. Could it even be possible that something's wrong with the camera itself?

At least I've got two Jupiter's in case I botch one.

 

[Mablo]

Have you tried your camera with any other lens than those three you mentioned above?

 

[capito]

Nope, the ministry of finance (my wife) has blocked all further expenses. 😉

But at the end of the month there's a camera fair in nearby Darmstadt, and I'll take a look there if I somebody has M or LTM lenses and will try it out.

 

[Sonnar Brian]

There is no way that 3 lenses can all be misassembled in the same manner. From the picture, the adapter looks okay. For the adapter to cause infinity to be at 3.75m, it would have to be much too thin. By the amount that the lens travels going from 3.75m to infinity. The adapter should be 1mm thick, you could measure it.

So- that leaves the RF of the camera being off. You need to check it with an M-Mount lens to be sure. If it does the same thing, it cannot be the adapter at fault.

 

[capito]

I sent the camera off to Zeiss last week and received it after only three days (yay!). And guess what, the rangefinder had to be realigned. It cost a very reasonable 95EUR, with a cleaning and new diopter eyecup.

The infinity problem is pretty much gone - there is just a little bit of play which I really would attribute to the adapter. I'm going to send off the first test roll today for development and am exited to see the results!

 

[Sonnar Brian]

Glad this the problem was solved, that is a weak spot of a rangefinder.

 

[kossi008]

Nice to hear that the problem has been solved. I was going to pitch in that the lens markings not lining up has nothing to do with it. My Heliar 75/2.5 did the same thing on my Bessa R (no adpater involved) and focused just fine.