Malfunctioning Jupiter-8

[vanyagor]

I was testing one of the Jupiter-8 I have recently aquired. This one was from 1958, silver, made at KMZ.

I have noticed that it can't be focused to infinity. I.e when I rotate the focus ring to the edn (and it is pointing to infinity sign at that position) the focus is infact closer!

Then I looked at the range of the rotation of the ring and it happens to be from infinity to 1.2 meter mark, although it is supposed to go down to 1 meter and even less (as all my other Jupiter-8s do).

Did anyone encounter such a problem? Can it be fixed?

Thanks

 

[Kim Coxon]

Hi,
Either the rear helix has been assembled incorrectly or the shimming is out. Should be fairly easy to fix. My instructions are here http://www.pentax-manuals.com/repairs.htm

Kim

 

[vanyagor]

Thanks a lot, Kim. Btw I just sent you a private msg concerning J-3. 🙂

 

[GeorgesGiralt]

Hi !
My J-8 of quite same vintage and from KMZ stops at 1.15 m .
I second the idea of one or more helix mis mounted.
A good chance to clean and re lube !
The trickiest part is to find a lube light enough to have a smooth focussing even with the 3 helixes... On my J-8 it is quite impossible. It is really smooth unlubbed but become stiff when lubed.

 

[Kim Coxon]

The problem tends to depend more on the amount of lube used rather than its thickness. Silcone based greases are better than the graphite ones but it is easy to apply too much.

Kim

Hi !
My J-8 of quite same vintage and from KMZ stops at 1.15 m .
I second the idea of one or more helix mis mounted.
A good chance to clean and re lube !
The trickiest part is to find a lube light enough to have a smooth focussing even with the 3 helixes... On my J-8 it is quite impossible. It is really smooth unlubbed but become stiff when lubed.