When you look at the difference in sharpness in the background gravestones, it seems to me that the 90mm ones are quite blurred. I am assuming that this is a reflection of the differences in depth of field, but would be happy to learn of other factors that may have caused this affect.
Theory and practice never seem to quite meet as expected in my experience, probably because of other factors that haven't been taken into consideration.
In this case there is the question of circles of confusion (which I don't have the figures for on these lenses) and the distance between the subject and the camera.
I think the distance figures might have been something more like like 3m and 5m (rough estimate based on using a zoom as the Contax G lenses don't have a distance scale), which would give a depth of field of 1.289m (35mm) and 0.52m (90mm).
Even these revised figures, although quite different, seen rather conservative compared to the pictures above which seem to show a bigger difference.
Anyway, whatever proves to be correct, it's nice to have a good discussion and chew over something other that the latest NEX equipment!