I just picked up my first 'blad from KEH this week. It is a black 501C with the acute-matte D screen. I am using it with a Phase One P21 and a 60/3.5 lens. The thing is I can't see to nail the focus to save my life. My old manual Nikon F series seem to be much easier to see when things are in focus. Is there a screen that gives much more snap to when things are in focus? I am using the PM90 BTW.