Leica 5cm Elmar focusing problem

[Niko]

I did a CLA last winter on my 5cm screwmount Elmar. All went well, except, when i tighten the lens properly on the camera (Leica IIIf) the focusing gets too tight. I can not understand what could cause this, the focusing helicoid should not be affected ??? Any ideas ? When i attach the lens loosely (too loose) on the camera it focuses smoothly, or when it is not on the camera it focuses perfectly smoothly. The grease i used in the CLA was a grease i once got from a Pentax -repairman, he said it´s for small lenses/short helicoids, i don´t remember what it exactly is.

Niko

 

[Erik van Straten]

Maybe the screw mount of the camera is not 100% flat. Try your lens on another camera or tighten all four screws of the screw mount on the camera. When the screwmount on the camera is not 100% flat, it will "bow" your lensmount and it will not move freely. Maybe the shimming under the lens mount of the camera is out of order.

Erik.

 

[Niko]

Thanks, Erik. There indeed is something wrong with the screwmount mounting ring. When i loosen the two upper mounting screws, the lens focuses normally. I then removed the mounting ring, there were no shims. I'll look at it closer later, for now i'm happy with it this way.

Niko