Need help with the first complex lens board I've ever seen

[SParis]

I bought an uncoated Zeiss 150mm Tessar in a Compur shutter. The glass is lovely, and the shutter works, but I can't figure out how to get it off of the lens board it's installed on.

I'm hoping someone here has seen one of these before. I haven't.

(Poor quality macro pictures below.)

Behind the shutter speed dial (12 o'clock) , there's a moving lever that engages a thin pin on the back of the shutter, to keep it from turning. This is normal for lenses of this age, and not a problem.

The problem is that at about 4:30 and 10:30 (looking at the shutter from the front) are heavy pins that are attached to the board. These pins are gripped by levers that do not move, even with heavy pressure, and also keep the shutter from turning. It's not possible to see what the inner end of these levers is attached to. (What I'm trying to do, of course, is unscrew the shutter from its retaining ring.)

I pushed on these with the tip of a screwdriver, hard, both to the left and inward. They don't move at all.

Releasing the normal pin-release lever and trying to turn the shutter on the board (to unscrew it from the retaining ring) doesn't work at all. Nothing budges even a little.

The thin black board is attached to the main gray board with 4 screws. The heads are behind the shutter and can't be reached.

Have you seen this before?

How do I get the lens off the board???

Second picture is the normal lens-release lever. Third and fourth pictures are the two mystery pins.

[Keith Pitman]

What does the back of the lensboard look like?

[SParis]

Forgot to say: There is a 3rd, thin board fastened to the back of the gray board. This one fits loosely around the back of the lens and would prevent access to the retaining ring, if there was one.
But I can see through the gap enough to tell that there is no retaining ring.

[SParis]

Keith,
There is a 3rd, thin round board on the back of the main board. The ends (not the heads) of 4 small screws protrude slightly.
Otherwise, it's as I described in the "Forgot to say" post.

[LabRat]

The retaining ring has to come off first, then lens should lift off board...

Ring needs proper spanner, or lens can be damaged when makeshift tool slips... Ring might be stuck due to corrosion or threadlok applied to threads... A few drops of acetone applied only to thread seam, and repeat should get the ring turning with a spanner...

Steve K

[SParis]

The retaining ring has to come off first, then lens should lift off board...

Steve K

I can see the shutter's threads on the back of the lens board. There isn't any retaining ring.
I'm wondering if the shutter is glued into the board.

I'd be willing to use a thin hacksaw and cut the two strange pins (doing my best to keep filings out of the shutter), but I'm hoping to hear from someone who knows exactly what this is, and how to unlock it.

(I guess another solution would be to buy a camera that uses 114mm boards.)

[reddesert]

You say you want to unscrew the lens from the retaining ring, but you also said that from the back, you can see there is no retaining ring. What is the lens screwed into, if anything? A picture of the back would help.

The large grey lensboard does not look contemporary with the lens or the small lensboard. It looks much newer, like it belongs to a postwar monorail. What is it like on the back? It looks to me like the small black board was mounted to the gray board by sandwiching it to the thing on the back, with the screws whose ends you can see. (If all else fails you can probably drill out those screw ends.)

Did you push on the two levers, or on the mystery pins? It almost looks like the pins are intended to be pushed down, pulled up, or slid sideways to free the levers.

[reddesert]

Based on your measurement of 114mm and the picture, the gray board could be a Rittreck lensboard. I've never had one, but it looks similar to pictures, such as those in https://www.largeformatphotography.i...ttreck-cameras

[SParis]

You say you want to unscrew the lens from the retaining ring, but you also said that from the back, you can see there is no retaining ring. What is the lens screwed into, if anything? A picture of the back would help.

The large grey lensboard does not look contemporary with the lens or the small lensboard. It looks much newer, like it belongs to a postwar monorail. What is it like on the back? It looks to me like the small black board was mounted to the gray board by sandwiching it to the thing on the back, with the screws whose ends you can see. (If all else fails you can probably drill out those screw ends.)

Did you push on the two levers, or on the mystery pins? It almost looks like the pins are intended to be pushed down, pulled up, or slid sideways to free the levers.

The lens appears to be screwed into a very tight hole in the large gray board, or maybe just a tight fit held in by whatever the mechanism on the front is, or by the 4 small screws that go into the back board. You're right, I misspoke about the "retaining ring." I just tried to unscrew the lens from the board.

Yeah, I'm considering drilling out the screws, although I'm not sure that would actually release anything. They're small screws, so I could even try prying the thin back board off of them.

I'll post a picture of the back tomorrow, when it's light in my elaborate studio.

Yes, I used a full-sized screwdriver (not jewelers-sized one) to push as hard as I could on both the levers and the posts, in every direction. The levers look like they're intended to move, but they don't.

[LabRat]

The small lever with the knurling might be a release lever, so try pushing it one way or the other and see if it disengaged something and releases something...

The grey board is an add-on to the smaller board and have been joined later... The retaining ring is probably under the black board, so first see how the two boards are joined, and held together...

Steve K