Dec 14, 2010, 3:19 PM
Registered: May 29, 2002
Nikon and Canon dSLRs, if they'll autofocus during video at all (I think only the Nikon D7000 will do this in the Nikon lineup, and I'm not sure about the Canon line) only do this with contrast detection, which is really, really slow.
Sony has a camera, the alpha55, that has continuous phase detection autofocus during video. It looks really, really nice.
demonstrates the speed of the AF.
I wouldn't switch from one of the big manufacturers to Sony just for this, but if you're buying a video-specific dSLR, you could do worse.
EDIT: Also, don't take all your video with your focus set to infinity. It'll look really amateurish. If you're going to spend all this money on a nice camera and glass capable of shallow depth of field, take advantage of it.
(This post was edited by styndall on Dec 14, 2010, 3:23 PM)