Focusing

[bkhan]

Having problem with my Leica M4 and 21 MM, is there any way to fix this problem

locally, focusing is not matching specially at infinety.

thanks bangash

[ronald_moravec1]

If the rest of the lenses focus properly, then no. It is most certainly a lens problem rather than a camera problem. If that is the only lens you have, there is no way to tell which has the problem.

 

About 98% of the time it is a camera rangefine problem, but you don`t want to adjust the camera if the lens is faulty.

 

Start by unmounting the lens and and clean the cam follower on the back of the lens and then the wheel at the top of the lens mount.

 

There are instructions posted here previously on how to adjust the camera. The lens requires profesional help.

[mike dixon]

What kind of 21mm lens do you have? If it's a thread-mount lens with an adapter (e.g. Cosina-Voigtlander 21mm/f4), the thickness of the adapter may be inaccurate.

[john_shriver]

Focused at infinity, the focusing cam should stick out of the lens the right amount. If it is an M mount lens, that amount is exactly 6.5mm. If it is an LTM lens, that amount is exactly 7.5mm.

 

An error is most likely because someone took the focusing helical threads apart, and put them together wrong. There's several "starts" to the threads, and at each point they have to be on the right start.

 

The other possibility is that the lens is out of collimation. Take some pictures measuring distances by hand, and focus by the numbers on the focusing scale. If they are not in focus, the collimation shims have been lost, again probably by an incompetent lens repair-person.

[ronald_moravec1]

How does this person measure 6.5mm accurately and not know how to adjust a rangefinder.

 

Any adapter needs to exactly 1mm thick. Leicas are always ok. My 6 CV are all ok. There are generics that are wrong.

 

Clean all mounting surfaces

[bkhan]

Hi folks,

Thanks for replies, using latest 21mm 2.8, (not thread one)

Thanks bangash