Originally posted by abruzzi I don’t know enough about how the body and lens communicate to have much idea where the issue might be.
Welcome to the club!
I had to do some thinking here. I am quite familiar with how the non-crippled K
A mount works, but the tough part is how the MZ-S drives the aperture number for the displays. Here are a few thoughts:
- P and Tv modes (camera controls aperture), the contacts on the mount communicate the minimum aperture and aperture range. See Features and Operation of the KA Mount | The K-Mount Page for details. For your F 50/1.4, the displayed apertures should be in the range 1.4 to 22. You should be able to test this in Tv (shutter priority) mode. If you are able to display numbers outside the actual range by changing shutter speed, there is a problem with the contacts on either the lens or camera.
- Av and M modes (aperture ring controls). For this case, the camera "knows" the same contact information as for P and Tv modes, but depends on the actual aperture ring position for display purposes. Metering depends on aperture position coupling tab on the body which engages a similar tab on the lens.
The display takes its cue from the position of the tab on the body. The maximum aperture position is the same for all K-mount lenses, while the minimum may vary depending on the range of apertures supported. In display purposes, the body "knows" the breakpoints between stops and will display as is appropriate with the minimum being either f/16, f/22, f/32, or f/45 depending on lens. Of course, this only works for lenses with contacts on the mount. (I'm assuming it works the same for A-series as for AF lenses.) For lenses without contacts, the display will be "F--" . Edit: Thanks to @Not_a_Number for clarifying a feature of the KAF mount. When the aperture ring on an AF lens is off the "A" position, the set value is passed to the camera through the "data" pin on the mount face.
If P and Tv modes display
only the correct range of aperture values while Av and M modes do not, the most likely cause is an
issue with the aperture position coupling between the lens and body or how the coupler position is interpreted within the body internal issue with the aperture ring position sensing on the lens.
Steve