On a whim I took 3 shots with three different lenses:
1. 80mm Summilux-R
2. 90mm Summicron-M (recent APO)
3 90mm Summicron-M (old vintage 1959 silver version)
While this is by no means scientific, I find it interesting how these three lenses do not show significant differences.
Can any of the forum members hazard a guess as to which lens is which.