Leica Jupiter 8 infinity focus on Leica

Riego

Regular
Apr 17, 2019
19
I have a Jupiter 8 from 1957. Is not adjusted for Leica but focus at one meter and wide open is very very close. The problem is the lens don't focus properly at infinity. The distance scale is at infinity, but the camera rangefinder is not.

Any advice? Can I easy fix the lens?

Thanks to all!!
 

BrianS

Super Moderator
Apr 3, 2013
124
I have a Jupiter 8 from 1957. Is not adjusted for Leica but focus at one meter and wide open is very very close. The problem is the lens don't focus properly at infinity. The distance scale is at infinity, but the camera rangefinder is not.

Any advice? Can I easy fix the lens?

Thanks to all!!
Is the problem that the RF Cam will not drive the camera's rangefinder all the way to infinity? If so- the easiest way to fix the problem is to build up the RF cam using Tape. I use 3M Copper Tape used for electronics. Most any good tape will do, but the copper tape can be as thin as 0.04mm. Before doing this- make some measurements at the 5meter mark for focus. Measure an object to be at 5meters, focus on it with the lens on the camera and see how closely the distance scale matches. If yours is measuring closer to 7meters, building up the Cam is the easiest fix.

The same technique can be used on most lenses where the RF Cam does not rotate as you focus.
 

Riego

Regular
Apr 17, 2019
19
Yes BrianS, that was the problem... but today I put the lens on my Leica III and it´s matching perfect at infinity. I don't know what happened yesterday :crying:

Thanks for your comment and MoomMind, thanks for your useful links!
 

BrianS

Super Moderator
Apr 3, 2013
124
The lens might have not tightened all the way into the mount.

The second explanation- sometimes there is a slight "wobble" in the helical. This can be corrected by relubing the lens, using a heavier grease. I use Vacuum Pump Grease for the worst wobble in my lenses.
 

Riego

Regular
Apr 17, 2019
19
The lens might have not tightened all the way into the mount.

The second explanation- sometimes there is a slight "wobble" in the helical. This can be corrected by relubing the lens, using a heavier grease. I use Vacuum Pump Grease for the worst wobble in my lenses.
I thought the lens was well lubricated, but it had some sticky grease.
Today I´ve removed all the grease and relubricated it. What a difference!

I´ve relube with "Lithium grease for general use". I do not know if it's the best for the helicoid. I´ve read that many recommend white lithium.

I do not know what exactly "Vacuum Pump Grease" is. Could you tell me a reference or comercial name to look for a similar one?
 

BrianS

Super Moderator
Apr 3, 2013
124
I normally use the general purpose white lithium grease.

Vacuum Pump Grease is a very heavy grease used for equipment in the lab. Used in a Vacuum environment, it has a minimum of "out-gassing". I use a 3M product. You can also find heavy grease used for plumbing applications in a hardware store. Use this heavy grease only for lenses with a lot of play in the focus.
 

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