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Help adjusting focus ring on Contax Zeiss 135mm f2.8
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PostPosted: Sun Feb 13, 2022 2:51 pm    Post subject: Help adjusting focus ring on Contax Zeiss 135mm f2.8 Reply with quote
Hello community,

I have a little problem with my Contax Zeiss 135 f2.8. Maybe someone can shine some light here.

The focus ring on my lens is a bit loose. It actually rotates quite easily, so I think it's not a problem with the helicoid but rather with the "outer tube". I have removed the rubber on the focus ring, to see if I could adjust the screws.
To my surprise, there is only one screw! After a few tries, however, I have not been able to move it. I've applied nail polish remover and used a 1.2mm flat head screwdriver, but it's already pretty tight and not going anywhere. I'm actually a bit hesitant to keep trying as I think the screw is already a bit worn out and don't want to do something irreparable. However, the ring the same as before.

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Is there anything else I could do? Perhaps disassemble the lens with rubber cones and remove the elements?
I've tried to look for a disassembly guide for this lens but haven't found anything. If any of you have seen one, I'd appreciate it if you could share it.

Cheers!
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PostPosted: Sun Feb 13, 2022 3:34 pm    Post subject: Re: Help adjusting focus ring on Contax Zeiss 135mm f2.8 Reply with quote
zeltraxnin wrote:

Is there anything else I could do? Perhaps disassemble the lens with rubber cones and remove the elements?
I've tried to look for a disassembly guide for this lens but haven't found anything. If any of you have seen one, I'd appreciate it if you could share it.


I have no experience with fixing Contax (Zeiss) lenses, but be careful with those little grub screws, they are easily damaged!

Without knowing what type of thread-lock they used for that screw (if any), it is hard to know the correct solvent to use. Sometimes acetone, sometimes alcohol, sometimes methylated spirits etc.

Did you leave the acetone to work long enough? Acetone evaporates very quickly and sometimes it needs a couple of minutes to soften the thread-lock all the way down into the thread...

Also, sometimes these grub screws simply get stuck, even if no thread-lock was used! (typically after an attempt to use either too wide or too thick a screwdriver which respectively either damages the inside thread or wedges the screw head tight into the inside thread). This is one situation where ideally you want to use a hollow-ground slotted screwdriver rather than the straight wedge-shaped ones.


PostPosted: Mon Feb 14, 2022 5:58 am    Post subject: Reply with quote
Maybe ,like a last chance, try using a soldering gun tip to heat it ,in my case it worked many times


PostPosted: Mon Feb 14, 2022 10:21 am    Post subject: Reply with quote
RokkorDoctor wrote:

I have no experience with fixing Contax (Zeiss) lenses, but be careful with those little grub screws, they are easily damaged!

Without knowing what type of thread-lock they used for that screw (if any), it is hard to know the correct solvent to use. Sometimes acetone, sometimes alcohol, sometimes methylated spirits etc.

Did you leave the acetone to work long enough? Acetone evaporates very quickly and sometimes it needs a couple of minutes to soften the thread-lock all the way down into the thread...

Also, sometimes these grub screws simply get stuck, even if no thread-lock was used! (typically after an attempt to use either too wide or too thick a screwdriver which respectively either damages the inside thread or wedges the screw head tight into the inside thread). This is one situation where ideally you want to use a hollow-ground slotted screwdriver rather than the straight wedge-shaped ones.


Thanks for the input. I'm afraid the screw may have got stuck as you mention on your last paragraph. I think I may have damaged it a bit...
I'll try to find a hollow-ground slotted screwdriver before touching it again. Just have to find out how those are called in Spain hehe

kiddo wrote:
Maybe ,like a last chance, try using a soldering gun tip to heat it ,in my case it worked many times


Thanks. Yeah, that's another option. I'll see if I can dissasemble the lens and take away the glass before doing that though.

It's definitely not the most expensive lens in my set so I thought it would be worth it to start fixing it on my own. 😅


PostPosted: Wed Feb 16, 2022 5:11 pm    Post subject: Reply with quote
I've not adjusted one but I believe that is the correct screw. At least, if you remove the front there are no obvious alternatives. If you do want to remove the front, grip the front of the lens and unscrew it. The dress ring is all part of it and doesn't unscrew separately.


PostPosted: Wed Feb 16, 2022 8:44 pm    Post subject: Reply with quote
kiddo wrote:
Maybe ,like a last chance, try using a soldering gun tip to heat it ,in my case it worked many times

zeltraxnin wrote:
Thanks. Yeah, that's another option. I'll see if I can dissasemble the lens and take away the glass before doing that though. . .


zeltraxnin, on my Contax 135 the focus ring is threaded and the single screw is just for security. So if you're able to loosen the screw, I think you should be able to tighten the ring just by twisting it.

As kiddo suggested, I'd also recommend heating the screw to help loosen it. Even just a hair dryer might be helpful.
And I'm not an expert, but I personally wouldn't worry about heat causing harm to the rest of the lens.
Unless the elements needed cleaning anyway, I wouldn't remove them from my own lens.

I took apart my Contax 135 a couple years ago and I made some rough notes of the process so I might be able to help if you have more disassembly questions. But for what it's worth, this wasn't the easiest lens I've worked on, so I'd advise you not to take it apart unless you really need to.


PostPosted: Fri Apr 22, 2022 3:15 am    Post subject: Reply with quote
55 wrote:

I took apart my Contax 135 a couple years ago and I made some rough notes of the process so I might be able to help if you have more disassembly questions. But for what it's worth, this wasn't the easiest lens I've worked on, so I'd advise you not to take it apart unless you really need to.


Hi, I would appreciate some help disassembling the helicoid from a Contax Zeiss 135mm AEJ if you have experience with this. I unscrewed the focus ring following the discussion above, and it revealed 6 grub screws which appeared to secure the rear helicoid half to the rear assembly. The problem is that even after removing these screws, the helicoid appears to be glued tightly to the assembly and will not budge after heating it with a hair dryer.

Do you have any tips to further disassemble/reassemble this lens? I made the mistake of unscrewing parts from the rear assembly which then became loose inside, and opened the lens to retrieve them. But I cannot put the lens back together while aligning the aperture lever and focusing posts. Removing the rear helicoid half appears to be only option left.


PostPosted: Fri Apr 22, 2022 7:23 am    Post subject: Reply with quote
Welcome, sapphire_jp.

It's too late at night for me to share my Contax Zeiss 135 work notes now, but I'll get back to you as soon as I can.


PostPosted: Fri Apr 22, 2022 6:22 pm    Post subject: Reply with quote
sapphire_jp wrote:

Hi, I would appreciate some help disassembling the helicoid from a Contax Zeiss 135mm AEJ if you have experience with this. I unscrewed the focus ring following the discussion above, and it revealed 6 grub screws which appeared to secure the rear helicoid half to the rear assembly. The problem is that even after removing these screws, the helicoid appears to be glued tightly to the assembly and will not budge after heating it with a hair dryer.

Okay... My 135 is also AEJ. And my memories of disassembly details are gone, so I'll just refer to my notes and hope they will make sense to you:

1 - Remove rubber focus grip.
2 - Loosen one screw at the bottom end of the focus ring. The focus barrel will unscrew.
3 - Loosen six screws in the distance scale piece. The scale will lift off.
4 - Turn upper helicoid / top end right until helicoid keys disengage. Unscrew upper helicoid.
5 - Turn lower helicoid right until it separates. (Count helicoid rotations and make reference marks.)
6 - To release elements / aperture module from upper helicoid / barrel, loosen three screws around upper helicoid (top).
7 - Unscrew large, outermost retaining ring around front element. Now module will lift out.
8 - Rear group is now accessible - unscrew.

You'll need a lens spanner for some of these steps. And retainers may be cemented in place, so solvent might be needed to help loosen them. Isopropyl alcohol is usually effective, but acetone will work faster.


sapphire_jp wrote:
Do you have any tips to further disassemble/reassemble this lens? I made the mistake of unscrewing parts from the rear assembly which then became loose inside, and opened the lens to retrieve them. But I cannot put the lens back together while aligning the aperture lever and focusing posts. Removing the rear helicoid half appears to be only option left.

It was difficult for me to get the rear parts / aperture levers back together properly. It took a lot of trial and error.
I have some brief notes about disassembling the mount if you have a specific question.
Can you post some photos of your situation?

Documenting lens disassembly with photos is tedious, but often helpful. Unfortunately, I took few photos of my process.
I have one photo of the inside of the bottom end of the lens. I noted there are spanner slots in the aperture stop down assembly and warned there are ball bearings which might fall out if the assembly is tipped.


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PostPosted: Thu May 05, 2022 8:55 am    Post subject: Reply with quote
thank you so much for this! Yes, I understand details vanish in your mind... Basically I am unable to accomplish step 3, even after removing the screws! Perhaps the scale is cemented, I will try to use your tips regarding solvent. If I am lucky with that, I will give reassembling the mount a go. Thanks again for the great reference.


PostPosted: Mon May 09, 2022 3:22 am    Post subject: Reply with quote
sapphire_jp wrote:
thank you so much for this!
. . .


You're welcome. I hope you'll succeed.


PostPosted: Sat Jul 30, 2022 5:20 am    Post subject: Reply with quote
Just to follow up, I was able to separate the focus ring from the helicoid following the advice here! Acetone and close heating with a hair dryer finally did the trick.

Reassembly unfortunately was frustration every step of the way. Sometimes it helps to not make them like they used to.

I managed to get it focusing correctly again, but the aperture ring/lever was inexplicably misaligned by one stop, and unable to reach wide-open. I searched but haven't come across such an issue in Contax Zeiss lenses before. I am using a work around by repositioning and attaching the lever with only one screw to the aperture ring, but if anyone has experienced similar issues I would love some ideas.
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