Stiff aperture ring on Zeiss-Opton Sonnar 50/2

[darkkavenger]

Hello,

I've got the feeling that my 50/2 Sonnar aperture ring is getting stiff, it is showing some resistance when turning it to select the aperture. It is usually stiff when lens if fully open or fully close. Do you have any advices on what can cause this and how it could be adjusted? Any skilled repairman among us? What can it cost? Maybe Brian can help? ;-)

Thanks for your advices.
Max

 

[Highway 61]

The Zeiss Opton Sonnar 50/2 has a fairly complex and weird (by comparison with the other lenses of that time) aperture ring mechanism inside, it's damped not only with grease but thanks to a leather cord that is enrolled around the inside barrel and on which the aperture ring has some friction. When this leather cord gets dry (and, at the same time, the original grease gets sticky) the aperture ring gets very stiff, particularly when you get close to f/2 and f/16, because the sticky grease has accumulated on both ends of the leather cord.

Time to open-up your Sonnar, remove all the old grease and the leather cord and replace it with a new one as well as cleaning the aperture module off all the old grease and applying a light amount of modern lithium grease where it ought to be !

🙂

 

[Sonnar Brian]

Missed this yesterday- repairing bathroom flooring is not as fun as lenses...


I never knew that about the 50/2 Zeiss Opton. I have two of them, worked on two others.

What I have noticed on the Zeiss Opton lenses: there are two distinct versions with unique optical fixtures. The serial numbers run concurrently.

Is the Leather Cord used in all of the Zeiss Optons?

 

[darkkavenger]

Highway61, thanks, it is exactly how it is currently happening: getting extremely stiff around f/2 and f/16. I do not really feel up to opening it, I have no precision tools to do that and I tend to get clumsy when working on something else than computers innards!

 

[Sonnar Brian]

Highway61, thanks, it is exactly how it is currently happening: getting extremely stiff around f/2 and f/16. I do not really feel up to opening it, I have no precision tools to do that and I tend to get clumsy when working on something else than computers innards!

Working on Computer Innards! You are fully qualified...

You need an adjustable spanner, available on Ebay. Front and rear optics come out, you get to the aperture mechanism. It is not hard, I basically bought some Junk lenses- learned to take them apart.

 

[darkkavenger]

Brian, thanks for the hints. I appear to have such a spanner, I will give it a try... Thanks!

 

[darkkavenger]

I've had a further look, I don't have the kind of spanner needed. I also had a look at Mike Elek's page here: http://elekm.net/zeiss-ikon/repair/sonnar-clean.html

There is no mention of the cord and of re-lubing the aperture ring. Any hints?

Thanks!
Max

 

[Sonnar Brian]

I have a junk 50/1.5 I will take a look at it.

 

[darkkavenger]

Thanks for the advices, Brian 🙂

 

[Highway 61]

I have fixed two Zeiss Opton 50/2 Sonnars, both had the typical leather cord, and both cords were in need of replacement by something more supple and less sticky.

Both lenses were early "chrome nose" versions. 🙂

 

[darkkavenger]

I am not certain whether I have an early version, but three pictures can be seen here:
http://www.flickr.com/photos/darkkavenger/sets/72157600010251077/

🙂

 

[Highway 61]

You have a "black nose" version, so, the second one. 😉

 

[darkkavenger]

Do you have any hands-on experience with those?

 

[Highway 61]

No but I bet they're 100% identical and that the leather cord is here between the outer chrome aperture ring and the inner black barrel.

I have carefully looked at Mike Elek's page re. the Opton 50/2 and it seems that he didn't take the aperture mech. apart on that very one.

You know - nothing "special" : only thing to do is to unscrew the three set screws which hold the aperture ring in place, then unscrew the aperture ring off the rear of the barrel, then you have access to the aperture module so that you can clean it in full by having it soak in lighter fluid, you will see a cam linked with a long set screw that drives the aperture blades, and the leather cord glued around the fixed housing barrel.

Most difficult task with these is not to marr the front namering with the spanner, and to very accurately collimate the lens using the special rotating ring designed for this.

The rear locking ring can be hard to remove sometimes too - and it's made of quite flexible white metal.

The prewar collapsible Jena Sonnar 50/2 and the immediate postwar Jena Sonnar 50/2 T are much easier to work on but servicing the Opton 50/2 isn't something very difficult, either.

 

[darkkavenger]

Thanks Highway61. This looks like a routine repair to experts, but knowing myself, I will probably "screw it up" at some point. Would you be able to recommend someone who can service the lens? I would like to exclude Henry Scherer due to his extremely long waiting list. Thanks very much!
Max

 

[aoresteen]

Try Don Goldberg. He has a backlog but not near as long as Henry's.

 

[aoresteen]

Another person who might service it is Pete Smith in Fl who works on Nikon SP cameras.

 

[darkkavenger]

Thanks, aoresteen. I am looking for a repairman in my area, either in Czech Republic or in Germany, will let you know whether my searches will be successful 🙂