What lubricant would you use on the coarse threads that move a lens in and out for focusing?
This thread is has a pitch of about 2mm. It's the one that moves the body of the lens in and out as the focus ring is rotated.
I feel that grease - such as lithium grease - seems a bit thick and draggy, though it would help damp and movement and cut out free play.
Would a thin machine oil be too thin?
Daniele