Is there life after aperture block failure?

flektogon wrote:

Futax wrote:

No, it won't stop down correctly if you set it to "A" (which is the equivalent to F22 or whatever as far as your camera is concerned). That would be just the same as using a lens without an aperture ring. Just set the aperture ring to your chosen aperture (which might well be an aperture which maximises sharpness), and in Av mode it will stop down to that aperture (at least with my K-50 it will).

Since the exposure metering is done just before you take the shot, and the camera assumes the aperture is wide open (it knows no different, as the aperture ring doesn't communicate back to the camera), the camera will overexpose unless the aperture is actually set to be wide open.

So you have to use exposure compensation to counteract this. For example, if it's an F4 lens and you set the aperture ring to F8, you will need +2EV compensation.

Give it a try, and report back, because that is how my own K-50 behaves, and I'm assuming it applies to all K-50s. It'll hopefully be of help to a lot of people!:-)

I am a little bit confused as why the EV correction has to be applied.

Exactly! Applying EV correction negates the claim that Pentax DSLR's work with full functionality with older manual lenses. I don't know how a camera with faulty ABF behaves, but my K-30 with K-50's firmware on it does not require any Abara-kadabralike painting the rear metal elements black, or fiddling with EV compensation