I managed to spend some time with my R snapping photos to learn how well it does, I even tried a old 35-80mm basic Canon lens with it, and it surprised me by how well it worked, AF was slow, of course, and at 80mm, the IQ was poor, but it focused accurately with no hunting.
Then, I had two Pentax M42 lenses at hand and I have several adaopters for them. I had wanted to try a 50mm f/1.4 that came my way for free, the front element was scratched up, and it was well used, but everything seemed to work. I was surprised and impressed with the brilliant colors and general IQ. I did try using the focus peaking with it, but it did not achieve critical focus, so I used the 5X setting and focused manually. That did a great job. Then, I tried a 2nf Pentax lens, a 50mm f/2. I was not as impressed with it, but it did do a good job.
Finally, I pulled out my 600mm Sigma mirror lens, thinking that focus peaking would make it a joy to use. Wrong again, I thought I had it nailed with the numerous different things I shot, but not one photo was well focused. I did not try the 5X magnification, I might yet do that.
I tried the 55mm Nikkor again using focus peaking for a close shot of the Sigma Mirror lens and it worked well. The camera was solidly attached to my light table. I compared it with a tethered manual focus using 10 X on my PC. It wasn't as good, but close.
I have dozens of various manual lenses, I may try some of my Olympus OM lenses as well.