Thanks for the useful thoughts. The 5D theory is interesting. And I guess it's, as David indicates, an emerging, amorphous kind of thing. I was watching episodes of "Alias," shot by Michael Bonvillian and so many times you see the actors move in an out of the very shallow focal plane. They'll be mostly in, but then just dip heir head forward or back and their eyes fall out of sharp focus. So, in those cases, you have a sense that a sharp focus is established and it's just that the focus puller is not compensating -- but not compensating because you can see (or it seems to me) that the focus isn't being pulled at all. They are just letting it happen and living with it. At first it can be disconcerting, but after awhile, you start to think, that's not being considered a mistake, even though it's probably not totally intentional either. It's just like relinquishing control a bit to natural forces. Saw this a lot on "Battlestar Galactica" too. But then, I just saw "Her," which employs extremely shallow DOF and yet focus never seems to be anything but sharp throughout. On the other hand, I also saw "American Hustle" this weekend, and in that film there seems to be dozens of sequences where it's not clear that focus was ever actually established. I suppose the only way to really know what's going on in a situation like that is to ask the cinematographer himself.