Yeah, not enough coffee - got my DOF and FOV mixed up.

In any case I find if you sit close to your camera, 35mm is a good FOV that will fit in your head and shoulders. The background blur for f/1.8 works well if you enable Servo Autofocus with Face Detect. It will momentarily get confused if you step out of the frame and back in again, but it can track a face pretty well after that.