Okay, this may be a stupid question but what exactly is the difference between the P and A modes on the D70(S)? In P mode the user scrolls with the thumb wheel through f stops and the camera determines shutter speed. How is this any different from A mode? I suppose I should have run into this question with my F100 since the behavior of these modes seem to be the same but I always use it in full manual mode, never in P or A. Any clues? Thanks!