I've been misunderstanding Ricoh auto-aperture lenses for a while, it seems.
But they look nearly identical on the lens! How could it not be working? Well, turn them over and count the contacts - that one pin that I felt certain was providing info to my Pentax was indeed not telling the camera anything of value. Well it must be saying something - but certainly not the calculated f/number. How sad, and how silly I feel - now I must go back and edit several posts here, wiping out the evidence of my error. But no, I am not wiping this away, it's a story that needs to be told one more time. After all, one less time and I was ensnared.
Despite this these Rikenon lenses are excellent, even more so now that I know every shot I took with them was wide open. I'm less certain that the 35-105 push-pull zoom will be great for video (it does fine, use anything but P mode!) but I still plan on trying to find out! I am glad I learned this before disposing of my Promaster 28-70, which is my only non-Pentax manfocus lens and therefore the proof I needed. Yup, in P mode the aperture lights up and tells me where I stand. Much better.