Can't unmount lens from its board

I recently found an interesting lens: a Tele-Congo 300mm f/5.6 in a Copal #1 shutter. It came mounted on a 8x8 cm lens board. I have no idea what kind of camera that's intended for. Now I want to mount this on a Graflex Super Graphic lens board. But I can't figure out how to get if off its current board. It's a raised board, so that makes it somewhat tough to work with. I could easily unscrew the rear element. Then I would have expected to just screw off the retaining ring and be done, but it's not that easy. I was able to loosen the retaining ring with a spanner wrench. I can turn the retaining ring a couple of times but then it hits a hard stop. There is a thin, smooth ring above the retaining ring. I think that's what's preventing it to come off any further. When I screw the rear element on, it ends up sitting flush with that thin ring. So I'm guessing this is some kind of stop ring that makes sure the rear element goes on at the right distance from the front element/shutter ???

There is no notch or anything on this thin ring that let's me get a grip on it. And it sits deep inside the extruded part of the lens board. If my guess regarding its function is correct, then maybe I shouldn't even try to get it off? It may have been glued or otherwise fixed into the exact right place somehow. And even if I get it off, I might not be able to put it back into its correct position later on?

Has anybody any experience with a lens mounted in such a way? What am I looking at here?

Worst case I can just leave the lens on its current board and mount the whole board on a Graphic board (which is larger). Is that my best course of action?

That is a Horseman board. The part with which you are having trouble is part of the rear cell that got inadvertently separated. Can you get it back together and try unscrewing the rear cell again?

ic-racer said:

That is a Horseman board. The part with which you are having trouble is part of the rear cell that got inadvertently separated. Can you get it back together and try unscrewing the rear cell again?

Click to expand...

Ok, didn't know it's a Horseman board. Thanks!

I tried your suggestion without success. The rear element screws back in until it sits flush with the part that's still on the shutter's thread. Both mating surfaces on the rear element and on this small part are perfectly smooth. I don't see how they could move together when unscrewing the rear element again. Nothing holds them together and there won't be much friction between them. There is also no room to get in my finger or anything else to grip both parts together when unscrewing.

Any other ideas?

If not I'll fall back to my lens board sandwich idea (Horseman screwed on top of Graflex board).
That would have the side effect of resulting in a raised lens board (which seems like a good thing for a 300mm lens?). Though it's going to take some effort to sandwich these together and make it all light tight and perfectly solid.

Soak by putting a lot of Acetone AKA Finger Nail Polish Remover around the threads of the ring and shutter. Allow to sit for 5 minutes to 10 minutes then try to unscrew the ring. A pencil eraser pressed against the ring at a 90° angle and kept at that angle when the ring moves may turn it. A rigid piece of rubber that fits between the ring and board edge may be needed to turn it. Once the thread locking agent has been released it may unscrew with the shutter mount ring.

Looking at Photo #2 does the retaining ring hold the shutter onto the lens board?
If so could be as simple as remove rear elements to gain access the with spanner wrench remove ring and then unscrew shutter assembly.

Just guessing?

jacaquarie said:

Looking at Photo #2 does the retaining ring hold the shutter onto the lens board?
If so could be as simple as remove rear elements to gain access the with spanner wrench remove ring and then unscrew shutter assembly.

Just guessing?

Click to expand...

That's exactly how to get it off.

jacaquarie said:

Looking at Photo #2 does the retaining ring hold the shutter onto the lens board?
If so could be as simple as remove rear elements to gain access the with spanner wrench remove ring and then unscrew shutter assembly.

Just guessing?

Click to expand...

Yes, the retaining ring holds the shutter to the lens board. What you see in photo #2 are two rings, though: there is a retaining ring closest to the lens board. It has the little notches that a spanner wrench can get into. Then there is another small ring above it. On the photo may look like just one ring. But it's two different rings and they sit on the shutter thread at a small distance from each other. I can easily get to the retaining ring with a spanner wrench and loosen it. Then it will rotate about one or two times until it hits the other ring right above it on the thread and comes to a dead stop. That second ring does not have anything that lets me get a grip with a spanner wrench.

I'm planning to follow shutterfinger's advice: loosen it up with Acetone and then try to get a grip with some kind of rubber.

Cut slots or drill indentation/holes into the smaller upper ring with a dremel and remove it with a spanner.

mjork said:

Yes, the retaining ring holds the shutter to the lens board. What you see in photo #2 are two rings, though: there is a retaining ring closest to the lens board. It has the little notches that a spanner wrench can get into. Then there is another small ring above it. On the photo may look like just one ring. But it's two different rings and they sit on the shutter thread at a small distance from each other. I can easily get to the retaining ring with a spanner wrench and loosen it. Then it will rotate about one or two times until it hits the other ring right above it on the thread and comes to a dead stop. That second ring does not have anything that lets me get a grip with a spanner wrench.

I'm planning to follow shutterfinger's advice: loosen it up with Acetone and then try to get a grip with some kind of rubber.

Click to expand...

You should only need to unscrew the retaining ring with the notches to remove.

mjork said:

Ok, didn't know it's a Horseman board. Thanks!

I tried your suggestion without success. The rear element screws back in until it sits flush with the part that's still on the shutter's thread. Both mating surfaces on the rear element and on this small part are perfectly smooth. I don't see how they could move together when unscrewing the rear element again. Nothing holds them together and there won't be much friction between them. There is also no room to get in my finger or anything else to grip both parts together when unscrewing.

Any other ideas?

If not I'll fall back to my lens board sandwich idea (Horseman screwed on top of Graflex board).
That would have the side effect of resulting in a raised lens board (which seems like a good thing for a 300mm lens?). Though it's going to take some effort to sandwich these together and make it all light tight and perfectly solid.

Click to expand...

This is a little unfortunate. What I would to is to use heat. I have never cracked a lens element, but you could remove all the front glass to be sure. Then heat it up and grab the light baffle with something like this or with a rubber Playtex glove to unscrew it. After removing the light baffle your lensboard would look like this and the shutter retaining ring would be accessible.