Quote Originally Posted by neuroanatomist View Post
With an f/2.8 or faster lens and a dual-sensitivity AF point (either an f/2.8 line + f/5.6 line cross type, or a dual cross type), focusing is a 2-step process - an initial focus move from an f/5.6 sensor line, then a refinement by an f/2.8 line.
Well that is interesting, because in my low light tests, I saw the focus move a lot, then stop, then couldn't see any other changes for a noticeable chunk of time, followed by the AF confirmation. So maybe it was "refining" focus and that was taking up some time.

If that is the case, then in situations like that, I could take the picture after the initial movement, and take it again afterwards, just in case the scene I'm trying to capture dissapeared before the final AF adjustment.