[torashi]

I'm thinking it's a lens issue, too. An A lens hast to establish a connection when it's set to the A position. I remember fixing an A50/2 because the metal parts that make or break the connection weren't doing it properly. Another A50/2 had those missing, because someone had also removed the spring and ball to remove the stops.
In any case, a bad connection can give false readings.
If you have a mutimeter, you can check the lens. Maybe even the contacts on the camera.

[stevebrot]

When I have the 50/1.4 mounted and the aperture set to A, the camera reports “Av” mode. (Or M if I hit the dial to change shutter speed.) I’ve pressed the green button on the front to reset to P mode, but it doesn’t change.

There is your smoking gun. The camera is not detecting the "A" contact on the lens and is showing what it believes is the set aperture from the aperture ring. You may want to contact KEH and ask that they repair the lens. Out of curiosity., does your lens lock in the "A" position in the same manner as your other F and FA series lenses?

Edit: Oops! Forgot that it is the camera that is a recent purchase, not the lens.


Steve

[butangmucat]

I think my second-hand FA31 had a similar issue before... It was fixed by a craftsman back in China by some simple disassembly and cleaning up the insides so that the A-pin can have a stable contact.

[abruzzi]

Out of curiosity., does your lens lock in the "A" position in the same manner as your other F and FA series lenses?

It does lock, but the aperture ring is clearly a little more worn as the detents are not as noticeable and it doesn't turn as smoothly as my 1.7. I may give it a shot to see if there is any internal cleaning needed on the electrics and anything else.