CZJ Tessar 50/2,8 front element problem

heresiarch · Joined: 08 Jun 2016 Posts: 15

Hello,

Recently I tried to clean fungus and stuck aperture on this CZJ Tessar. I ran into a problem when I tried to take apart the front element.

Here's the lens

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And here's how the front element came out

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It looks like the first and second element are somehow stuck together. I tried to open them with considerable force, even with pliers, but I'm afraid that I will damage the lens if I continue. Does anyone have any idea how to disassemble them? Thanks. Here's the imgur link of the pics

http://imgur.com/a/NauXz

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calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

Tervueren · Expire: 2014-11-08

http://oomz.net/tessar/

heresiarch · Joined: 08 Jun 2016 Posts: 15

heresiarch · Joined: 08 Jun 2016 Posts: 15

Just figured out that forum prevents pictures on the first post. I thought I was losing my mind. Thanks to user calvin83 for reposting.

Lloydy · Expire: 2022-01-01

The Tessar should be an easy lens to take apart. the front ring is usually hand tight and has no glass. The front glass is then removed by undoing the retaining ring with the two holes for a wrench.

I've just tried to remove the whole piece as in your pictures and can't shift it.

heresiarch · Joined: 08 Jun 2016 Posts: 15

Yes. That's what I was looking for! This helps me a lot.

Can you bear with me just a little bit, please? In your opinion, should I try to unscrew the two parts (pictured in my photo no. 3) or should I try to pry them open? I'm not sure what keeps them together so tightly that I can't separate them.

Thank you very much for your help

Lloydy · Expire: 2022-01-01

The thread you want to unscrew is the one under this thread that is visible. As a starting point, I would lay this part on a level table and flood the front trim ring with lighter fuel to a point where the threads are covered, let it soak for a few hours, and then try unscrewing the two parts. The lighter fuel should creep through the seized thread, and will do no harm to anything else.

heresiarch · Joined: 08 Jun 2016 Posts: 15

Thank you Lloydy for your help. I soaked the rings for hours, but without result. Those two damn parts are like welded together. What's important is that I now have information that there are no screws or any other things (besides black magic, it seems) that holds these two together. I'll continue to try but with better equipment. If I succeed I'll post the results.

I would like to thank everyone for help once more.
I'm new here, just discovered the wonderful world of old lenses. I already saw that the forum is very nice with lots of helpful information for a beginner like me. Hope to stay around and learn.

Lloydy · Expire: 2022-01-01

Maybe try hot water in the ring? Use rubber gloves to grip the two parts, it's surprising how much more grip you get. I also use silicone sheets, you get them from supermarkets - used in cooking for something? While in the cooking utensils department, look for jar lid grips, they're dirt cheap and some are very effective.

heresiarch · Joined: 08 Jun 2016 Posts: 15

Made it! I gave it that "one last try".
Here are the two elements separated:

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For future reference, if someone runs across the same problem:

I jammed the screwdriver between the front element retaining ring (black) and front casing (purple). They were glued together with some incredibly strong unholy black glue.

But, unfortunately, it seems that this was the easier part. I need to clean fungus that grows between front and second element which are inside this black assembly that now looks even more impenetrable. So, I'll must ask another question: Is there any way to separate them?

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Lloydy · Expire: 2022-01-01

Great result! Like 1 small

But that's it, those two elements are in a block that is swaged together so there is no access to the facing sides of the elements. ( I've got one in bits in front of me right now. ) but try cleaning what you can get at, it's surprising how much difference it can make

If you remove the rear elements you can then flush the whole thing with lighter fuel to get the oil off the blades without removing them. It's not the perfect way of doing it, that needs a full strip down to get the old lube out of the helicoid, but it's good enough to make the Tessar a very good user lens.

And sitting here with one of mine in bits, I really can't understand how the front trim ring was stuck to the lens block so tightly? The only thing I can see is that the trim ring and the lens block have different thread pitch, when you unscrewed the ring the block started to move as well and moved at a bigger rate than the trim, which then 'riveted' itself onto the block.
The trim ring should just slip over the front of the lens block, so before you reassemble it might need slightly relieving?

heresiarch · Joined: 08 Jun 2016 Posts: 15

Damn. I kinda expected that there's no way inside it. I already serviced the rest of the lens, thanks to that great oomz tutorial. Cleaned the aperture, relubed, cleaned the fourth element, everything. The cleaning of fungus from the two front elements was the last thing to do. Such a shame it's impossible. I'll try to kill them with the sun so they don't spread further.

Well, the lens gives nice results even in this state and it was 10€ so I guess I cant complain. Also I learned something in the process.

Thanks again Lloydy, you've been of great help.

Lloydy · Expire: 2022-01-01

I was lucky, the one I just had apart had a tiny bit of fungus on the outside / rear of the front block so it's perfectly clean now. Which is nice for a �2 lens I found in a box of junk at a camera fair that was otherwise mint. Now I have three Tessar's. Rolling Eyes