[English-Photographer]

I have a 55mm f1.2 Porst lens on the Pentax K1 and can't get the aperture to work and perhaps it's just a simple menu fix?

The lens is old and doesn't communicate with the body. And that's fine. I can deal with the F - - for the aperture and manual metering.

But the aperture ring doesn't work. Ah ha! Time to use the green button for stop down metering as works on my friend's manual lens. No luck on the 55mm nor does the aperture change when you shoot.

What am I missing? Are my only options to shoot everything wide open or to file off the catch on the lens that keeps the aperture open when it's attached to the camera?

Thanks!

Ben

[Na Horuk]

Stuck aperture is often a problem with that lens, according to reports. Feel free to search some threads about this, or read here: Porst 55mm F1.2 Color Reflex MC Auto Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

Since it has no A mode on aperture ring, you cannot select aperture from camera anyway, and it will always say F---. Nevertheless, you should go to Menu of camera and near the back Enable the Aperture ring use. But this, or even green button metering, will not fix a mechanical lens problem

[UncleVanya]

A few lenses have painted mounts that stop electrical contact with the body. I can't recall the exact symptom but I know a fix is to apply a small bit of foil on a spot on the mount - can anyone clarify if that could apply here?

[D1N0]

Check this topic: https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...-k-30-etc.html

If it doesn't work either the contacts aren't shorted out (use a piece of tin foil) or you have sticky aperture blades (clean them). by the way the only reason to have a F1.2 lens is to shoot it wide open. You can do that in any mode.

[marcusBMG]

apply a small bit of foil on a spot on the mount - can anyone clarify if that could apply here?

More on this here:

https://www.pentaxforums.com/forums/116-pentax-k-r/271872-tests-plated-vs-pai...r-whats-t.html

[Ken Pimontel]

A few lenses have painted mounts that stop electrical contact with the body. I can't recall the exact symptom but I know a fix is to apply a small bit of foil on a spot on the mount - can anyone clarify if that could apply here?

Yes. The Porst does not short the contact. Add foil.

[English-Photographer]

Excellent thanks! It was the black anodising coating on the lens ring. I filed it off and it works fine now. Lovely lens, totally different character at f4 and beyond so a nice versatile beast.