[joachim]

Your AF ideas about DSLRs live in the past still... The 5D mk III is very capable of focussing accurately with very shallow DOF. And fast at that.

 

Toni-a, I forgot which lenses you have. Of course, lenses play a big part in the result. For portrait, FF makes more sense unless you never use shallow DOF in portraits.

 

There is shallow, very shallow and extremely shallow.  On my books a 90/4 (equivalent) is between shallow and very shallow.  This typically leads to one eye being out of focus, so one has to pick the "leading eye" with the AF or hope for the face detect to do that for you.

 

Coming from µFT with its pretty efficient face detect (incl. eye priority) I am honestly wondering how one would do that on an SLR when using a finder.  I understand these don't offer eye detection when not in a "live view mode".  Background: I am chasing toddlers with a 45/1.8 (90/3.5 equivalent) in lowish light (ISO 1600, 1/60s, f/1.8).