Hi all,
Does anybody have detailed experience of repairing a Carl Zeiss Jena Tessar 50/2.8 Zebra M42 please? This came to me with sticking aperture blades and a loose focus ring. The lens was very oily/greasy from someone else's botched previous attempt and the blades were flooded. I have sorted that but can't stop the focus ring loosening. If you look at the image the focus ring is secured by a notched spanning wrench ring (the outer notched ring). When I tighten the ring and then turn the focus it loosens again and repeated movement of the focus ring just undoes the the ring. I am reluctant to use more than a smear of oil on the mating surface for obvious reasons.
It is almost like there is a thin slip ring missing or the notched ring needs to have thread lock to stop it moving. This type of lens is new to me and I haven't stripped one before. I have looked at a schematic which suggests there isn't a part missing but I can't work out how to stop the ring unscrewing :-( .
Anyone know the answer please?
Thanks Nick