Repairing Contax Zeiss 35mm f2.8, advice needed

[Zang]

Hi all,

I have recently purchased an used Contax Zeiss 35mm f2.8. The focus ring is more stiff than I like so I decided to take on the lens overhaul. When I could not find anything on the internet for the lens, I mostly work based on guessing. The first step to remove the front barrel was successful. After that, my guess is I'll need to remove the front objective assembly. I see a locking ring underneath the assembly and I tried to unscrew it. The challenge is, it is so stubborn that I fear I might break the focusing keys if I try harder. My questions are:

1) Does anyone have experience working with the lens?
2) Based on the picture here, does it make sense to remove the locking ring as the next step?
2) What is your suggestion for dealing with the stubborn ring? I tried a lot of nail polish remover and I am reluctant to use penetration oil.

Thanks in advance.

[Erik Lund]

Not shure what mount this is but it looks similar to this one:
https://www.youtube.com/watch?v=oGJpmTslWfQ

[Zang]

Not shure what mount this is but it looks similar to this one:
https://www.youtube.com/watch?v=oGJpmTslWfQ

Thanks Erik. Mine is Contax/Yashica. It is very different than the one in the video.

My thoughts are, even though if the bronze ring is not the next step, it would not cause any harm if I unscrew it now. The only challenge is, it sits very tight. Tighter than in any lens I have ever worked on.

[Zang]

I am giving up with removing the front group for now. I have opened the back and I can confirm that the helicoid keys are accessible from the front side

I can see the outer helicoid threads are exposed a bit from both front and rear sides depending on either the focus ring is at infinity or minimal distance. Do you think putting some penetrating oil to thin the existing grease a bit is a good idea?

[Gone]

I wouldn't - you will end up with oil / oil vapour all over the glass and insides of the lens.

If you don't know what you are doing then leave it alone unless you are prepared to scrap the lens - even if you manage to disassemble clean and assemble it again there is no guarantee it will be correctly calibrated and inevitably, without a clean room, dust and fibres will find its way into the lens.

[Zang]

I agree with not putting oil, Chris...

Regarding giving up, it is always an option. Let me keep it as the suicide bullet then I feel worse when I give up than when I screw up things LOL.

[Zang]

There were moments when I thought I'll give up