Carl Zeiss Jena Tessar Zebra 50mm Focus Frozen

Paragon · 09-24-2022, 12:18 PM

Hi guys and girls!

I just got myself a Carl Zeiss Jena DDR 50mm f2.8 Tessar (zebra) for 10 USD. The lens is in good shape, a few marks and dings on the casing but the glass looks to be in great condition.
However, this whole lens was absolutely frozen.

I managed somehow to remove the outer focusing mechanism from the optics and gave everything a good clean, however, I have discovered that the outer focusing (the focus ring and the other ring that has the thread) are completely frozen. I have tried everything from WD-40 to isopropyl alcohol. It only moves about an inch back and forth and that's it.

What should I do from here?
Pics below:

Attached Images

**Stefan Jr** · 09-24-2022, 11:50 PM

Message removed by me- because it was inaccurate. Early morning mistake.

.

Paragon · 09-25-2022, 01:55 AM

Originally posted by Stefan Jr

The general rule is; that the focus ring is locked in place with a small stop screw. "About" a ½ to 1 twist before they are fully married. Once the the stop screw is removed, the focus ring and the helicoid are separated by anti clockwise action.

So the first question is: Have you removed the stop screw?

I'm not sure exactly that I removed the stop screw. But in many videos with this lens being taken apart, the outer focusing mechanism is freely moving, while mine feels like it's glued.

---------- Post added 09-25-22 at 02:03 AM ----------

Does anyone have a photo of this focus stop screw? I'd like to know if I already took it off. Thanks!

---------- Post added 09-25-22 at 02:15 AM ----------

Edit: Just tried to heat the outer focus rings, did not help at all. Both are welded in place, and I can't figure out how to get them separated or at least moving.

**Stefan Jr** · 09-25-2022, 02:26 AM

Just ignore my answer. I'm not familiar with this design. And was confused.

Hopefully you'll get help from someone that is.

You'll probably already seen this tutorial, but if not, look here:
https://richardhaw.com/2021/10/17/repair-carl-zeiss-jena-tessar-50mm-f-2-8-zebra/

Best of luck,

Paragon · 09-25-2022, 02:30 AM

Originally posted by Stefan Jr

Just ignore my answer. I'm not familiar with this design. And was confused.

Hopefully you'll get help from someone that is.

You'll probably already seen this tutorial, but if not, look here:
https://richardhaw.com/2021/10/17/repair-carl-zeiss-jena-tessar-50mm-f-2-8-zebra/

Best of luck,

Hmmm, wait a second! Retaining ring?!

---------- Post added 09-25-22 at 02:37 AM ----------

Yes, the retaining ring is stuck as well.

Paragon · 09-25-2022, 03:11 AM

I made it!

Heated the outer again, then aplied ample amounts of WD-40 and then forced the retaining ring until it moved and started to loosen.

---------- Post added 09-25-22 at 03:23 AM ----------

The inner helicoid is stuck just like the rest of the lens. WD-40 time it is!

Paragon · 09-25-2022, 06:21 AM

Well, I have reached the point where I do not know what to do. The inner helicoid will not move at all.

I am open to suggestions.

**Joetitch** · 09-25-2022, 08:12 PM

As a suggestion of last resort, heat the whole lot in an oven to 100°c
Provided that there are no springs or plastic to be damaged. Cool by dropping into pot of room temp oil.
You could possibly heat it hotter but I would be cautious. Then again as it is not working, what have you got to loose?

**pentaxus** · 09-25-2022, 10:47 PM

Something that frees stuck metal like that is PB blaster which is available at auto parts stores. It soaks in well and has a really strong smell so use it in a well ventilated area.

Reed · 09-26-2022, 03:03 AM

Maybe this will help a bit, I don't use WD40 on lens housings and helicoid, as I've found that much better results for stuck optical grease/adhesives etc is done by slight heating(~80-90° C) and dripping acetone in all the recesses with syringe needle to loosen those stuck parts.

**JoelA** · 09-26-2022, 01:45 PM

Just a head's up. I do use PB Blaster on vintage bicycles where there is steel to aluminum bonding. It does work, eventually.

That said, I'd be sort of thinking "last resort" to use it on anything that gets near optics. PB Blaster does its job but I'd be very concernced about anything with fine threading like a lens. It's tough stuff to clean up after in small/tight applications.

And as the previous poster noted, it really stinks! (And stains too...)

Paragon · 10-02-2022, 11:55 PM

Sorry for the late reply guys. I have not messed with the lens since my last post. I am taking a short break from it otherwise i'll lose my patience and damage it further.
What I will try to do is use a small file and try to deepen the factory grooves in the helicoid, by doing this I hope to be able to get a better grip on the threads.
Apart from my plan of messing with the factory lens spanner holes, I have been dropping acetone in between the lens and the helicoid, I will try some lighter fluid as well.

09-24-2022, 12:18 PM	#1
Paragon Forum Member Join Date: Oct 2021 Posts: 60	Carl Zeiss Jena Tessar Zebra 50mm Focus Frozen Hi guys and girls! I just got myself a Carl Zeiss Jena DDR 50mm f2.8 Tessar (zebra) for 10 USD. The lens is in good shape, a few marks and dings on the casing but the glass looks to be in great condition. However, this whole lens was absolutely frozen. I managed somehow to remove the outer focusing mechanism from the optics and gave everything a good clean, however, I have discovered that the outer focusing (the focus ring and the other ring that has the thread) are completely frozen. I have tried everything from WD-40 to isopropyl alcohol. It only moves about an inch back and forth and that's it. What should I do from here? Pics below: Attached Images

09-24-2022, 11:50 PM	#2
Stefan Jr Site Supporter Join Date: Jan 2015 Location: Sweden Posts: 338	Message removed by me- because it was inaccurate. Early morning mistake. . Last edited by Stefan Jr; 09-25-2022 at 02:31 AM.

09-25-2022, 03:11 AM	#6
Paragon Forum Member Join Date: Oct 2021 Posts: 60 Original Poster	I made it! Heated the outer again, then aplied ample amounts of WD-40 and then forced the retaining ring until it moved and started to loosen. ---------- Post added 09-25-22 at 03:23 AM ---------- The inner helicoid is stuck just like the rest of the lens. WD-40 time it is! Attached Images

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09-25-2022, 01:55 AM	#3
Paragon Forum Member Join Date: Oct 2021 Posts: 60 Original Poster	Originally posted by Stefan Jr The general rule is; that the focus ring is locked in place with a small stop screw. "About" a ½ to 1 twist before they are fully married. Once the the stop screw is removed, the focus ring and the helicoid are separated by anti clockwise action. So the first question is: Have you removed the stop screw? I'm not sure exactly that I removed the stop screw. But in many videos with this lens being taken apart, the outer focusing mechanism is freely moving, while mine feels like it's glued. ---------- Post added 09-25-22 at 02:03 AM ---------- Does anyone have a photo of this focus stop screw? I'd like to know if I already took it off. Thanks! ---------- Post added 09-25-22 at 02:15 AM ---------- Edit: Just tried to heat the outer focus rings, did not help at all. Both are welded in place, and I can't figure out how to get them separated or at least moving.

09-25-2022, 02:26 AM	#4
Stefan Jr Site Supporter Join Date: Jan 2015 Location: Sweden Posts: 338	Just ignore my answer. I'm not familiar with this design. And was confused. Hopefully you'll get help from someone that is. You'll probably already seen this tutorial, but if not, look here: https://richardhaw.com/2021/10/17/repair-carl-zeiss-jena-tessar-50mm-f-2-8-zebra/ Best of luck,

09-25-2022, 02:30 AM	#5
Paragon Forum Member Join Date: Oct 2021 Posts: 60 Original Poster	Originally posted by Stefan Jr Just ignore my answer. I'm not familiar with this design. And was confused. Hopefully you'll get help from someone that is. You'll probably already seen this tutorial, but if not, look here: https://richardhaw.com/2021/10/17/repair-carl-zeiss-jena-tessar-50mm-f-2-8-zebra/ Best of luck, Hmmm, wait a second! Retaining ring?! ---------- Post added 09-25-22 at 02:37 AM ---------- Yes, the retaining ring is stuck as well.

09-25-2022, 06:21 AM	#7
Paragon Forum Member Join Date: Oct 2021 Posts: 60 Original Poster	Well, I have reached the point where I do not know what to do. The inner helicoid will not move at all. I am open to suggestions.

09-25-2022, 08:12 PM	#8
Joetitch Site Supporter Join Date: Aug 2016 Location: Leura NSW Posts: 502	As a suggestion of last resort, heat the whole lot in an oven to 100°c Provided that there are no springs or plastic to be damaged. Cool by dropping into pot of room temp oil. You could possibly heat it hotter but I would be cautious. Then again as it is not working, what have you got to loose?

09-25-2022, 10:47 PM	#9
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,320	Something that frees stuck metal like that is PB blaster which is available at auto parts stores. It soaks in well and has a really strong smell so use it in a well ventilated area.

09-26-2022, 03:03 AM	#10
Reed Pentaxian Join Date: Mar 2015 Location: Warsaw Photos: Gallery Posts: 638	Maybe this will help a bit, I don't use WD40 on lens housings and helicoid, as I've found that much better results for stuck optical grease/adhesives etc is done by slight heating(~80-90° C) and dripping acetone in all the recesses with syringe needle to loosen those stuck parts.

09-26-2022, 01:45 PM	#11
JoelA Loyal Site Supporter Join Date: Feb 2019 Location: Florida Photos: Gallery Posts: 187	Just a head's up. I do use PB Blaster on vintage bicycles where there is steel to aluminum bonding. It does work, eventually. That said, I'd be sort of thinking "last resort" to use it on anything that gets near optics. PB Blaster does its job but I'd be very concernced about anything with fine threading like a lens. It's tough stuff to clean up after in small/tight applications. And as the previous poster noted, it really stinks! (And stains too...)

10-02-2022, 11:55 PM	#12
Paragon Forum Member Join Date: Oct 2021 Posts: 60 Original Poster	Sorry for the late reply guys. I have not messed with the lens since my last post. I am taking a short break from it otherwise i'll lose my patience and damage it further. What I will try to do is use a small file and try to deepen the factory grooves in the helicoid, by doing this I hope to be able to get a better grip on the threads. Apart from my plan of messing with the factory lens spanner holes, I have been dropping acetone in between the lens and the helicoid, I will try some lighter fluid as well.