How to adjust infinite on Ultron 28mm 1.9?

[Yves]

Hi,
I have a nice Ultron 28mm 1.9 (LTM) which does not focuss correctly fully open (at 1.9). Focus is in front of the focussed distance and it could be set to beyond infinite.
I compared to some leica lenses as reference and am sure it needs adjustment. The camera used to check is spot on (R-D1s)
Does anybody know how the re-adjust the lense?

Thanks, Yves

 

[flip]

Just curious.... Did you use that adapter with other LTM lenses successfully?

 

[ferider]

Hi Yves,

as flip suggests, it might be a problem with a cheap LTM adapter.

If the adapter is OK, and the lens actually front focuses (easy to check with a close up test shot), you can adjust this:

Remove the lens mount. Underneath you will see a black ring. You can adjust the infinity focus by loosening the screws that hold this ring and moving the black ring just a little. Tighten the screws, put the mount back on, try it out, repeat procedure if not yet correct.

Here you can see how it looks for a 35mm Ultron - the 28 is - I believe - the same.

Best,

Roland.

 

[Yves]

Hi Roland,
perfect, that is what I was looking for.
The adapter is a "cheap" one, but they are all within the +/- 0.02mm tolerance, it is the lens.

Best regards, Yves

 

[Yves]

Hi,
I bought a good pair of screwdrivers and tried to adjust infinite. But I did not managed to remove all of the screws. The outer 3 screws hold just a ring with the dof scale. Then there are 6 screws which are very tight, probably glued in. Something moved anyway and the error is in the other direction now... So I will continue to investigat theis weekend.
Yves

 

[Yves]

Hi,
finally the lens is focussing correctly now - after several hours of twiddeling around... I think the screws holding the rangefinder coupling helix were a bit loose and the mechanism became misaligned.

All cound be done from the front, the back of the lens does not need to be disassembled and better shouldn't.
So I removed the front ring, then the aperture adjustement unit and the the lense body. There are 3 screws in the back holding the rear helix to the part acting on the rangefinder cam. IN my case they were not tight and caused the misadjustment. In case adjust to correct infinit, thighten them. Then put the lensbody back and put in the 3 screws holding it to the front helix but don't tighten them yet. Now adjust the helix until focus is correct and tighten them. Resassemble it all.

Best, Yves