Aperture on Tele-Xenar 4/135 does not open all the way - why?

Started 5 months ago | Discussions
xtam667 Regular Member • Posts: 221
Aperture on Tele-Xenar 4/135 does not open all the way - why?

I have got this vintage Schneider-Kreuznach lens in DKL mount. I push the aperture lever to the max but the aperture does not open all the way like in any other lens I have seen:

This is supposed to be the f4 max aperture on a 135mm lens

What is with this lens? It is near mint and the aperture lever and focusing ring work fine. Another thing I noticed is that it closes to a much smaller opening at f22 compared to another 4/135.  A mystery to me given how good the condition of the lens is and apparently working as intended.

Lightshow
Lightshow Veteran Member • Posts: 7,722
Re: Aperture on Tele-Xenar 4/135 does not open all the way - why?

xtam667 wrote:

I have got this vintage Schneider-Kreuznach lens in DKL mount. I push the aperture lever to the max but the aperture does not open all the way like in any other lens I have seen:

This is supposed to be the f4 max aperture on a 135mm lens

What is with this lens? It is near mint and the aperture lever and focusing ring work fine. Another thing I noticed is that it closes to a much smaller opening at f22 compared to another 4/135. A mystery to me given how good the condition of the lens is and apparently working as intended.

Sounds like the aperture mechanism has slipped somewhere, either the aperture ring, or most likely the aperture basket has either set screws or a jam ring that has become loose the basket has shifted.

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OP xtam667 Regular Member • Posts: 221
Re: Aperture on Tele-Xenar 4/135 does not open all the way - why?

Lightshow wrote:

xtam667 wrote:

I have got this vintage Schneider-Kreuznach lens in DKL mount. I push the aperture lever to the max but the aperture does not open all the way like in any other lens I have seen:

What is with this lens? It is near mint and the aperture lever and focusing ring work fine. Another thing I noticed is that it closes to a much smaller opening at f22 compared to another 4/135. A mystery to me given how good the condition of the lens is and apparently working as intended.

Sounds like the aperture mechanism has slipped somewhere, either the aperture ring, or most likely the aperture basket has either set screws or a jam ring that has become loose the basket has shifted.

Thanks. Is this complicated / costly to repair?

Rol Lei Nut Veteran Member • Posts: 5,889
Re: Aperture on Tele-Xenar 4/135 does not open all the way - why?

DKL mount lenses have two aperture levers (one isn't so obviously visible). One sets the aperture and one opens and closes the diaphragm when the shutter is released (when used on its original bodies). It could be that the aperture setting one is set to closed down a bit.

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