Agfa Anastigmat Apotar 10.5 cm - servicing the focusing mechanism

Romanko

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I'm cleaning Agfa Anastigmat Apotar 1:4.5 10.5 cm lens salvaged from an Agfa folding camera (Agfa Billy?). The lens is a triplet. The rear element was easy to remove and cleaned well. The focusing ring did not move at all even after applying considerable force with a friction tool. The front element in its tube is supposed to unscrew easily but this is not happening. It could be damaged, cross-threaded or glued with an old grease. So I removed the scale-ring, the infinity stop and using a lens wrench unscrewed the front and the middle elements together. See photos.


I assume the Apotar is focused by rotating the front element inside the lens tube that holds the middle element. Is this so?

Then, what prevents the middle element from unscrewing from the shutter body as you focus?

Also, what is the safest and easiest way to separate the middle and front elements which currently appear to be glued together?



Shutter assembly with middle and front elements removed.



Middle and front elements removed from the shutter.
 

albada

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Your assumption of how it should focus is correct.
You are a victim of Agfa's infamous Gluey Green Grease used to lubricate focus helicals. Over the years, that grease hardens. Some folks have softened the grease and unscrewed the two brass pieces by letting them soak in naphtha for a day. Heating that assembly in an oven to cooking temperature always works for me, but you would be taking the risk that uneven thermal expansion might crack the glass.

After separating them, I suggest cleaning out all the old grease by soaking them in naphtha and scrubbing the threads with a toothbrush.

Mark
 
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Romanko

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albada said:
You are a victim of Agfa's infamous Gluey Green Grease used to lubricate focus helicals.
Click to expand...

So I thought. I am in no rush and I'll start by letting naphtha (available as Shellite in Australia) work its way into the thread.
 
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Romanko

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Using a fine paint brush I applied some acetone to the threads and scrapped it with a toothpick. A small amount of wax-like substance of blueish-greenish color was removed from the thread. The parts are still glued together. They are left in a zip-lock bag.

albada said:
Heating that assembly in an oven to cooking temperature always works for me
Click to expand...
What is your "cooking temperature"? Does it melt the glue grease or just softens it?
 

Dan Daniel

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You can try ammonia, also. Needs to soak for a few hours. The problem is that it will also remove paint so be careful or avoid if this is an issue. Looks as if you could put your lens flat, rear to the bottom, and dribble around the joint between the front and back lens into that threaded connection.

If you want to heat, I suggest keeping the temperature low. Maybe 140F/60C? Hot water temperature plus a nudge. At the most a double boiler set up, keeping it below 200F/90C
 
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Romanko

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Dan Daniel said:
The problem is that it will also remove paint so be careful or avoid if this is an issue.
Click to expand...
This is my main issue with using strong solvents like acetone and ammonia.

Dan Daniel said:
Looks as if you could put your lens flat, rear to the bottom, and dribble around the joint between the front and back lens into that threaded connection.
Click to expand...
I can but then the assembly will be resting on the glass surface which is not ideal. I ended up holding the assembly in one hand and applying small amounts of acetone to the joint with a brush.

Dan Daniel said:
Maybe 140F/60C? Hot water temperature plus a nudge.
Click to expand...
I'll repeat the acetone trick a few more times before I resort to heating.

Sous Vide Apotar, Monsieur?
 
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Romanko

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Heated it to 100C in the oven and tried to unscrew.
No luck.
I need to make a couple of beefy lens tools/clamps and try again.

Agfa should have patented this stuff and sold it as Loctite.
 

albada

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Romanko said:
What is your "cooking temperature"? Does it melt the glue grease or just softens it?
Click to expand...

Around 150 C. That softens the Green Gluey Grease enough to unscrew the helical. I've done this to several 35mm Agfa cameras with 5 cm Apotar lenses, and haven't cracked one yet, but I have not tried it on the 10.5 cm lens.

Mark
 
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Romanko

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Success! Heated to 140 C and used two home-made lens tools to unscrew the front lens. There was quite a bit of resistance. I cleaned the Green Cluey Grease while it was still warm using Q-tips and ethanol. I need to clean it better as it is still very sticky. The thread is very fine and could have been damaged though it is not obvious.


 
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DareFail

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Romanko

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"chain cleaner" is most likely kerosene.

I finally managed to get rid of the remaining Agfa Grease. I used Shellite (Ronsonol/lighter fluid), a lot of Q-tips and a brush to get the solvent into the thread. The thread is not damaged and the front element rotates quite nicely. It might even be a bit loose but a new grease will take care of this.

I now need to clean the shutter and find a camera to put it in.
 
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