Repair of a pre-war 8.5cm (85mm) f2 Carl Zeiss Jena Sonnar in Contax mount

TenEleven

TenEleven

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Normally this would be where I post a guide on how to disassemble and service such a lens, but this one has me stumped.

Everything seems to hinge on me not being able to get the lens cell (with the aperture mechanism) out of the focus mount.

I do not think that the threads are seized up because the lens looks as if it has been serviced in the last 10 years since the aperture is oil-free and the glass is sparking clean. The inside parts I could access were also all clean. I have also used two ring wrenches and the front of the lens is very grippy so this should work, but the way it does not even budge a little bit makes me think Zeiss has hidden some grub screw in there to hold the lens unit in place.

My question is where?

part_1.jpg
The focus scale ring can not be removed because it bumps into the aperture actuating ring, which bumps into the lens head.

part_2.jpg
The depth of field scale similarly bumps into the focus scale ring...

part_3.jpg
This is how far I got.
The rear lens group can also not be removed (but can be rotated a bit) since while unscrewing it bumps into the rear section of the focus mount....

Any help or hints would be hugely appreciated.
 
What is the Serial Number of the lens? There should not be any hidden set screws holding the barrel in the mount.
I have seen lenses Glued in place. I know one that was glued in by Henry on a 5cm F1.5 Sonnar and would not come out.
 
I just tried to unscrew my 213 series 8.5/2 lens. On there really tight, twisted as hard as I thought prudent, it did not budge. My 201 series unscrewed no problem, it was snug but yielded to moderate twisting. Given that the design of the 201 series and 213 series lenses are identical, I am guessing that old solidified grease may be the culprit. I know that there should not be any grease on the threads that hold the thing together, but you never know.
 
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My 8.5cm F2 Contax Mount lens 223xxxx- easily unscrews, has been CLA'd.

If you can get the glass out, might want to let it soak.
 
Thanks for all the replies!

So I guess it should just unscrew. I was unsure since most other pre-war lenses I know have grub screws securing the optical block. (In my experience: Tessar 2.8cm, Biogon 3.5cm, Sonnar 5cm both versions)

Sadly I can't get the rear group out since its hitting the focus mount. I assume its hitting the bottom most protrusion that's visible in dexdogs picture. Otherwise I would have already made my peace with having to repaint the index scale and just let it soak.
 
I have an early-ish (1962) Jupiter 9 that I assume is the exact same design. The front does just unscrew to take the optical block out.

I'd get one of those jam-jar openers and give it a go with that. Obviously make sure you grip on the end of the barrel and not the aperture ring, though!
 
The Contax mount 8.5cm F4 Triotar, 8.5cm F2 Sonnar, and 13.5cm F4 Sonnar: all unscrew from their mounts. No set screw holding them in.
 
Actually Brian, that depends on the particular person that made the lens. After yesterday I asked my work colleague to bring his 8.5cm over which I had previously serviced.
Because I faintly remembered there being a set-screw and - yes there was.

Not the best picture, apologies. But you can sort of kind of see the set screw in there. You have to turn the focus to see it. This copy is a Carl Zeiss Jena 8.5cm Sonnar with a serial of 1.9million and has been coated. As one would expect it's fully brass and also heavy.

screw.jpg

@dexdog maybe that's what held your other one in. Worth a look.
 
TenEleven said:
Actually Brian, that depends on the particular person that made the lens. After yesterday I asked my work colleague to bring his 8.5cm over which I had previously serviced.
Because I faintly remembered there being a set-screw and - yes there was.

Not the best picture, apologies. But you can sort of kind of see the set screw in there. You have to turn the focus to see it. This copy is a Carl Zeiss Jena 8.5cm Sonnar with a serial of 1.9million and has been coated. As one would expect it's fully brass and also heavy.

View attachment 4851948

@dexdog maybe that's what held your other one in. Worth a look.
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TenEleven, I looked at both of my lenses, they look the same. I assume that you mean there is a set screw inside the hole in the mount when focus is set to infinity. Don't have the best light right now, will check tomorrow morning. I did see what looks like penciled numbers next to the hole in the mount for the 213 series lens, though.
 
You have to turn the focus to see the set screw through the hole of the mount (which does not rotate only the toothed part does) since the set-screw rotates together with the optical block.

My colleagues' was visible at about 10 meters on his meter scaled lens. The hole was populated with a standard grub style set-screw which pierced the bottom of the optical mount. This is coincidentally similar to how it's done on the post-war Opton 85mm lenses as well.
 
TenEleven said:
You have to turn the focus to see the set screw through the hole of the mount (which does not rotate only the toothed part does) since the set-screw rotates together with the optical block.

My colleagues' was visible at about 10 meters on his meter scaled lens. The hole was populated with a standard grub style set-screw which pierced the bottom of the optical mount. This is coincidentally similar to how it's done on the post-war Opton 85mm lenses as well.
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Both of my lenses are marked in meters, went through whole rotation of focus and did not see any set-screws. I will look again tomorrow when I get sunlight through windows.
 
TenEleven said:
I've enlarged and brightness boosted the section with the screw. And yeah - even in doing so it's not super visible.

View attachment 4851964
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I checked mine- does not have the hole for the set screw. I'll know what to do if I work on one that does not come out.
I have a few CZJ 13.5cm F4's- all just screw out. I have a Zeiss Opton- would not budge. I will check it!
 
My F-coated Z-O 85/2 has 3 set screws through the base holding the thing together. You can see one of them about 10 o'clock on the interior of the lens barrel.
 
I just unscrewed my 201 series 8.5cm/2 lens, including removing three tight-fitting shims totalling about 0.46mm thick. There is definately a hole through the mount (perhaps 1mm diameter) in the area that TenEleven indicates, but mine has no set screw. I could see light shining through the hole when I held it up before a really bright flashlight. In any case, the set screw woulda been under the shims, but I guess tightening it against the shims would help hold the optical block in place. On this particular lens, I had to twist the optical block firmly to get the aperture mark to index with the infinity line on the focus mount. If this lens originally had a set screw in place, it would have dimpled the thin copper or brass shims, and I see no evidence of that.

With regard to the 213 series lens that I have not been able to unscrew, there is definately a small depression or dimple in the lens mount in the area that TenEleven pointed out, but I cannot ascertain whether there is a screw or not. I tried the Vessel 0.9mm screwdriver that I typically use on those tiny grub screws and could not get a grip on anything, although I did succeed in making a bit of the brass in the dimple shiny!
 
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Well... this certainly did not went as I hoped.

First I tried @Coldkennels suggestion. I really leaned into it and heard a crack. Thinking myself successful I undid the wrenches and had a look. Turns out I somehow had managed to mutilate the mount section despite using a strap wrench. I assume the strap must have caught on the protrusion of a screw and pulled on it? Yet despite this excessive violence the optical block had not even moved a single millimeter!

Well now I was in for it anyway - so I unscrewed the focus portion as shown in the pictures above again and put some IPA around the rim where I could see the edge of the thread of the optical block. I also heated the lens and waited for 2 hours like that. After 2 hours I noticed that some of the IPA had condensed onto the lens. Expected but it meant that I was running out of time.

So pipe wrenches round two. I took out the grub screws for the focus and aperture rings in order to not mutilate anything any further. After lots of exhaustive twisting and jerking and even using a hammer to tap on one of the wrenches to persuade it (the other in a vice) ... nothing moved. As the inimitable Chris Sherlock says: Bad words were said.

Well with the IPA in there at least the lens had to come out or I would lose the lovely and completely pristine glass also. So I drilled a pilot hole from the back and applied downward pressure. Then more twisting. Nothing again. So ultimately I basically drilled a series of holes until I could use a vise to literally pry the part that holds the optical block apart and lift the optical block out.

Once I had done that ... it was STILL stuck in there. More bad words. Finally sort of resigned I pulled on it as hard as I could and it came free with a loud CRACK. The shims tore apart. One of the shims one was really stuck on there it would not come off holding the block to the mount. And then I realized...

Some... .. uh .. per...son... had superglued the shims to the optical block. Of course in screwing in the lens the glue got squeezed out and ran into the thread. Brilliant work. The added thickness of the glue is likely also why the focus was slightly offset (not reaching infinity completely).

Here is the optical block after lapping out the holes from the drilling as well as using a blade to get out all the superglue from between the threads and more lapping. The aperture mechanism was still full of the brown smelly old grease that Zeiss used. So they had not even changed that. Just miraculously the aperture itself was clean.
done_2.jpg

Here's the "finished" frankenlens - using the focus mount of a coated but very cloudy lens as donor. I re-did the aperture of course and also the focus mechanism which is now very light and moves smoothly again. I still have to set/shim the infinity focus, that will happen when the sun is out tomorrow.

done_1.jpg

Is it as pretty and shiny as it was before? Sadly no, this copy is a lot more used looking. But frankly I would rather have a lens that works - and I also do not feel responsible for this at all. I mean superglue?!

I do not know what else I could have done in order to save the other focus mount. I saved the focus scale and focus ring among other parts - but Zeiss being Zeiss they did not fit on the other lens despite it being of the same era.

Long story short, the theory that Brian voiced earlier (glued lens) was the correct one.

PS: Even when it screws apart easily - the pre-war 8.5cm has to be my least favorite lens to service in Zeiss lineup. The focus section is a nightmare. The later Opton version is a lot easier and much more sensibly laid out.
 
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TenEleven, nice work salvaging that lens! Why would anyone superglue shims? I still recall my lone interaction with superglue...someone had glued a Lietz 3.5cm adapter to a Nikkor 3.5cm/1.8 in LTM. Nothing would dissolve that bond. Finally took a dremel to it and ground away part of the adapter, was able to peel it off with pliers. Luckily, the lens survived, it has beautiful glass and still threads onto cameras and adapters just fine.
 
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santino said:
Congrats. Why do people even bother to glue shims to the lens block???
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I wish I knew.

My initial assumption was they did not have enough shims (despite it being comparatively easy to make more) for their desired flange-distance and the superglue was a way to hold the lens in place and stop it from rotating.

But, the shims were compacted tight so I doubt my theory now. What a waste...
 
This thread has convinced me to leave my pre war uncoated 8.5 cm Sonnar alone even though there does appear to be some haze in the rear element group. The film that I've shot with it looks fine so I'm not touching it unless someone has a great repair person to recommend that doesn't have a 3 year waiting list.
 
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