Specs...Lens: 25-50mm f4 AIS Camera: Nikon F4 with MF23 back
Tested out my new used 25-50mm AIS lens on the F4 when I went on a street shoot today, and noticed that although its an AIS lens, and matrix metering works with it (seriously, I've never used the Matrix Meter before, prefering to use Central-weighted or Spot meter), when you're on "A" (aperture priority) and one of the "P" (programmed) modes, no aperture information shows up on the MF23 back. This also means no aperture info is imprinted on to the film. I usually set the MF23 to print shutter and aperture setting information between frames, but with AIS lenses, it seems that it only prints shutter speed and you get a "--" for aperture.
When you set the F4 to "P" mode, the body doesn't seem to be able to set the aperture on the camera, even if you stop it down to the smallest aperture setting. In effect the "P" setting works like "A" where you set the aperture using the aperture dial on the lens.
Don't matter to me too much since I'm mostly on aperture priority or full manual.