@rainier,
I don't doubt your knowledge let me set that first.
What I meant to say is that even with the same or different lens choices there is a difference in the endresult (workflow).
For the same portret with the same lens you have to step closer to the model with a MF format, and thus rendering a different look.
It's hard to explain on a forum what is meant, and probarbly my example doesn't come over the way I intended.
What I'm trying to say is that with the bigger sensor and the lenses for MF you can achieve a different look than with a DSLR.
I did try some tests ,before I switched, with the 120mm macro on the 645AFD/III and a 85mm on the 5D and when comparing those shots there was a much more pleasant compression on the 120mm macro shot with the Mamiya than on the 85mm on the canon 5D.
With the MF system I can shoot at 210mm wide open (f4.5) and throw my background completly out of focus, standing in the same location with the 70-200L f2.8 I can not achieve that to this extend, I can throw it out of focus a bit but not as creamy as with the 210mm on the MF (distance model / background / photographer is the same).
The reason for this (or at least I thought it is) is that the focal length of 120mm is different than the 85mm and when standing at the same location there is a difference in behaviour, called it FOV or compression. Or at least that's my experience, but I could be totally wrong so if you can point me in a right direction I would love to read about it (one learns every day).
My simple conclusion was as follows.
When I shoot a person with a 200mm lens the DOF will fall off quicker than with a 135mm lens (same crop, FOV)
When we now replace the lenses for cameras one could say (or at least that is my conclusion) that we can now shoot with a person with a longer lens from the same distance and thus have a quicker fall off of focus and more compression.
Sample shot by the way with the background, this was by the way just a test shot so nothing special but I hope it explains it a bit:
This is shot at the narrowest part of the old studio and with the 5D I could not get the background and focus on the model like this, not even with the 70-200L f2.8 wide open (by the way could not shoot at 200mm with that lens due to space limitations). So I was limited to the same place on both cameras.
Hope this helps a bit with what I'm trying to say. (always difficult on a forum).