Zeiss Flektogon 50/4 (Medium Format) assembly question

[nandakoryaaa]

Hi!

I recently finished repairing a Zeiss 50/4 for medium format. The aperture was stuck so I disassembled the lens down to the smallest part and assembled it again.

I should say beforehand, that there is no possible way to assemble it wrong. I intently searched for many possibilities but they don't exist, so I can be pretty sure about that. There are different details that can be put only one way and not another, so I got the lens back together and all parts are now working normally, except for one peculiar thing.

The inner aperture drive is working like it should - when turning around, it makes the aperture fully open or fully close. It is limited by its own means.

Next, the aperture ring is connected to the drive with a pin that is protruding from the inner surface of the ring and when you turn the ring, it also turns the drive with this pin.

All in all, it is normal. But the aperture ring has its own limiter. The pin moves inside the cut-off space of the outer lens barrell. It naturally stops after reaching the edge of that space.

And now, what is the problem: The pin is more limited than drive. So when the pin reaches either end, the drive can still move further. So the aperture does not fully close and does not fully open by about one stop.

It can be entirely possible that the lens was originally like this. But I don't know about that because the aperture wasn't working and I couldn't see it.

I have some strange idea that this lens could be an f/2.8 lens instead of f/4, but it is intently limited. It's like some gadgets or cars which characteristics are artificially lowered in order to sell a more pricey model which is basically the same. But could this be possible with lens?

To fix the problem I can just cut off some more space from the lens barrell and the pin will move further (the ring will also go beyond "4" and "22" marks on its scale). But I don't know, is it really the right thing to do, or am I missing something? I will provide photos of the lens if needed.

Oh, forgot to say. There is a small setup piece in the drive that can be moved left or right thus limiting the drive more or less to either side. With it, I can make the aperture open earlier so when the aperture ring hits the "4" digit, it will be fully (or almost fully) open. But at the same time it will lose the ability to close for the same amount.

[Gerald]

[nandakoryaaa]

[Gerald]

You should not need to do any surgery on your lens for the diaphragm mechanism works as it should. Maybe you have assembled something incorrectly.

Below the pictures of my lens at F4 and F22. Note the positions of the iris blades and the pin you mentioned.



Wide open - F4:



Stopped-down to F22:

[nandakoryaaa]

[nandakoryaaa]

[Gerald]

Happy ending after all!
Fortunately you did not file the pin stops!

[nandakoryaaa]