Dismantling Zeiss Biotar 2/58 M42 lens

[bobm]

Anybody know how to dismantle a Zeiss Biotar 2/58 M42 lens?

The lens internals need a clean & regrease but I can't get the rear lens retaining rings to budge and I'm unsure if the black front part unscrews to allow removal of the front lens element.

Any ideas as to how I can free off the retaining rings and how to extract the front element would be most appreciated.

Thanks in advance.

Bob

[mickeyobe]

Bob,

I just examined my f2/58mm Biotar. Exakta mount.
I am not going to be much help but I can see that there are 3 retaining rings on the back.
The smallest, inner one, appears to hold the rear element in place.
The largest, outer one, appears to have been worked on as the blacking is removed from inside the notches. Perhaps this is the one to remove. Could it have a reverse thread?
Just an uneducated guess.

Mickey

[bobm]

Thanks Mickey - I've tried the usual tricks like using rubber mat to grip the edges etc. but none of those two rings seem to want to move either way and I can't get the front to come off either - assuming it actually does. I don't know about the Exakta fit Biotar, but on the M42 one, the outer of those two rear rings is very close to the lens mount thread and there's not a lot of room for access to the notches. I will however, try the outer again but in reverse as you suggest, as you never know.....

My problem is that I need to access both the front and rear of the lens so I can remove and clean the elements as there's some fungus & haze that I want to deal with quickly. The removal of the glass will also make things easier for dealing with the focus helix and aperture control as the grease has dried out and causes both focus and aperture rings to bind..

I'm waiting on an Exakta fit Biotar arriving so I'll get a look at that when it comes.

If I get this sussed, I'll post my findings etc. up here as a guide to others.

Speaking of which:
www.kyphoto.com/classics/forum/messages/6899/6252.html

[mickeyobe]

Bob,

Try this for complete diagrams and instructions.


Mickey

[bobm]

Mickey, you are a star, what can I say but thank you so much.