Cleaning a Carl Zeiss Sonnar 50mm f1.5

@simonOWO
There are two different versions of the 50mm F1.5 West German Sonnar- getting the aperture ring off is very different. I think yours is the more difficult version.
That version- as you found out, the set screws couple the ring to the movement of the blades. The "easier" version using a screw in pin like a wartime Sonnar.

What are you trying to do by taking the lens down further?
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@Sonnar Brian

The movement of aperture ring is stiff, feels like some dirty thing got into the threads (if there is any threads under aperture ring like the other type) I am trying to do a CLA, and potentially a color mod of the exterior, make the lens all black
 
Hello Brian,
I have been reading this thread with great interest.
I have a Zeiss Opton 50mm f1.5.
I only want to collimate it, so believe I don't need to dismantle it further than just removing the outer ring at the rear so that the lens body can be removed from the mount.

But my problem is that the outer ring seems to be well and truly stuck. Even applying as much force/torque as I can reasonably do using a lens wrench, it won't budge. What is considered to be the best next move in such a case?
 
Sonnar Brian said:
@simonOWO
There are two different versions of the 50mm F1.5 West German Sonnar- getting the aperture ring off is very different. I think yours is the more difficult version.
That version- as you found out, the set screws couple the ring to the movement of the blades. The "easier" version using a screw in pin like a wartime Sonnar.

What are you trying to do by taking the lens down further?
View attachment 4853550View attachment 4853551View attachment 4853552View attachment 4853553
Click to expand...
Looking back at this thread, can we say that we have 3 versions? Inside pin, outside pin, set screw?
 
I have had that happen a number of times. What I do: a slight amount of Lighter Fluid or 99% alcohol to free it up. Slight amount, applied to that outer ring. Then- spanner that fits nicely into the slot.
 
It's been a while- but on the stuck retaining ring problem, I remember removing the rear group to get easier access to the retaining ring. Meaning with the inner rings out of the way, able to get easier access to the slots of the retaining ring.
 
Many thanks Brian and Peter.
Indeed I do think it's better to remove the rear group first; I followed your advice Brian. 3 reasons: 1) it allows better access to the stuck outer retaining ring (and if really necessary you could devise a special tool to fit across the castellated slots in the retaining ring, thus giving better engagement and more controlled leverage; 2) you don't risk damaging the rear element in case of accident/slippage; 3) it allows a more direct route for the freeing agent (I used lighter fluid) to get down into the thread, without being potentially obstructed by the ring holding the rear group.

Anyway, mine was well a truly stuck and it took me several goes over a couple of days, but eventually it shifted.
The strange thing is that when it was all apart there was nothing indicating why it should have been so stuck, such as corrosion or muck. I can only think that it had been done up very tight and/or there was some micro adhesion somewhere.

All done now, though, and the lens is back together.
 
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