I must confess, David, that I even have "misplaced" my universal focussing screen on the R9. I prefer the full matte screen in all circumstances on an SLR. It must be my RF background. I hate obstructions between myself and the photograph. But common knowledge, and common sense, I suppose
- find the universal screen with central focussing wedge and microprism ring the most versatile for fast (say faster than f 4.0) and short (under 90) lenses. Which means that quite a few modern zoom lenses suffer from blackout on the focussing wedge and even on the microprisms, as they run into 5.6 as max. speed.