OK..... lets elaborate on the autofocus of the 3 MFD systems.
Phase One:
Three focus sensors located very close to the center of the screen.
No indication of which sensor locks or attempts to lock focus.
Focus lock indicator is at the bottom of the screen.
No end user calibration can be performed.
No auto compensation of focus when focusing and recomposing.
EDIT:
The focusing on the DF camera has two settings. Speed and more accurate.
The fast setting searches for focus and locks in one go.
The more accurate setting (the default) searches for focus, does a preliminary lock and then does a little hunt to fine tune the focus lock.
The speed setting is not accurate at all and the manual recommends using at least f8 for this setting.
From the manual:
C-19 AF Priority [AF_2]
Accuracy of auto-focusing priority (default setting) or speed priority can be
decided.
0: Speed
(Aperture to f/ 8 is recommended when using this function.)
I found the speed setting to be pretty much useless.
Hasselblad H4:
Only center focusing point, but the system includes true focus that auto adjusts focus when recomposing significantly improving focus and making the use of auto focus on features away from the center of frame in the final composition way more accurate. The photographer however has to take care not to move forwards or backwards when recomposing.
Pentax 645D:
User adjustable focus calibration.
11 point focus sensor with precise focusing screen indicators. Also indicates what point is locking focus. Has focus sensors most spread out for a MFD system permiting more accurate focus and less focus and recompose.