[Nick Rowland]

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

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[PJ1]

I have two of those and both could do with a helicoid lube job (one day). Anyway, I googled "disassemble and clean tessar 50mm f2.8"and got more than I needed. One site looked like it might have the answer. In it he refers to a locking ring being sealed with a small dot of varnish. So maybe locktite is the way to go:

Carl Zeiss Jena 50mm f/2.8 strip down and clean ? Simon Hawketts' Photo Blog

Let us know how you go.

[Nick Rowland]

Thanks PJ, I had read that article buy completely missed that comment, probably because it was referring to a different ring and I didn't make the connection. Yes, if one ring was secured by a dab of varnish, others might have been too. I'll try 4 dabs of varnish (it's a big ring) and see what happens.

Cheers
Nick

[clickclick]

Not uncommon to find a dab of I believe shellac to lock threads from original assembly when taking apart old lenses. Some clear nail polish will work just fine. If you use Loctite, make sure to use the weakest formula - don't use the red.

[Nick Rowland]

I've looked through a loupe at other threads and I can see signs that it has been used before. I'll do the same I think, I tend to use clear nail varnish and it has worked before.

[clickclick]

I tend to use clear nail varnish and it has worked before.

Nice and easy and readily available.

[Nick Rowland]

Just a follow up, it was all sorted with a couple of small blobs of nail varnish and working fine. Only small issue was setting the infinity focus point but that doesn't take long.

[TwoUptons]

So do we get to see it all back together?

-Eric

[Nick Rowland]

So do we get to see it all back together?

-Eric

Here you go, a poor phone pic but shows the finished article. Have another to do now.

[TwoUptons]

Here you go, a poor phone pic but shows the finished article. Have another to do now.

It’s a cool look. I like it. Thanks.

-Eric

[Nick Rowland]

It performs quite well and was a popular lens in its day. The problem with most of them now, is the helical grease has gone hard and the focus stiffens right up. Folk then squirt thin oil in to free up the focus and the oil sooner or later ends up on the aperture blades.

[clickclick]

Looks nice. Always satisfying to have them back together and working.