question re aperture on karl zeiss jena 180/2.8 pentacon 6

Started 2 months ago | Questions
TFGJR Junior Member • Posts: 35
question re aperture on karl zeiss jena 180/2.8 pentacon 6

Greetings.  The aperture on this lens seems to be stuck wide open, but I just want to be sure I'm understanding the mechanism correctly before I venture inside.  First, when the "plunger" (the silver pin) is pressed down (toward the front of the lens), you should be able to control the aperture with the aperture ring, yes?   Second, am I right that the function of an adapter would be to keep the plunger engaged so that you can control the aperture with the ring?

Thanks!

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Rol Lei Nut Veteran Member • Posts: 4,660
Re: question re aperture on karl zeiss jena 180/2.8 pentacon 6

TFGJR wrote:

Greetings. The aperture on this lens seems to be stuck wide open, but I just want to be sure I'm understanding the mechanism correctly before I venture inside. First, when the "plunger" (the silver pin) is pressed down (toward the front of the lens), you should be able to control the aperture with the aperture ring, yes?

Yes.

Second, am I right that the function of an adapter would be to keep the plunger engaged so that you can control the aperture with the ring?

If adapting directly to digital, yes. The original Exakta and M42 adapters would activate the plunger mechanically.

Thanks!

Just for the record: I went to check my 180 2.8 and 300 4.0, which I haven't used for years, to confirm what I wrote. On both of them, the diaphragm is stuck wide open...

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