Summicron-M 50 stiff focus problem....?

[daryl_jorud1]

Lens is type 4 Summicron-M 50/2. Body is M6 TTL. With lens

unmounted, focusing ring rotates reasonably smooth, with only the very

slightest increase in resistance noticed at midpoint of focus arc.

However, once lens is mounted to camera body, focusing stiffens

noticeably at midpoint (6feet) until close focus is reached. Why the

difference when mounted?

My theory is that the focusing helix becomes "steeper" somewhere

around midpoint, which translates into more resistance. Will a relube

of the helix smoothen this out.......or might there be another

problem, such as a slight deformation of something in the lens body

once mounted to the camera body?

[andy m.]

Send it to a decent tech. They will diagnose the problem and the good ones won't charge you for anything that isn't necessary.

[__jon__]

I had the same problem when my M6/50mm 'cron took a fall. I loosened up the mount

screws on the lens and then retightened them. The mount had been shifted slightly off

and that was causing the binding.

 

Might be worth trying this out before you send it to DAG or another repair person.