Quote Originally Posted by Feanor
But in very low light, where AF-assist beams are not allowed, I find that the outer AF points are almost useless. The center AF point still does the business but at f2.8 focus recompose doesn't really work, especially with anything that is moving even slightly.

Yeah, I agree. In low light I use the center point and recompose, which works fine for me because usually my subjects aren't moving. Keep in mind, though, the full frame sensor allows you a lot of freedom to crop compared to a crop sensor. So for small far away stuff that is moving in lowish light, I use the center point and compose by cropping.


One more point: the 7D has auto focus is rated to work in the same light as the 5DII (-0.5 ev). Maybe all the af points work as well as the 5DII center point, but we don't know that for sure (I don't, at least []). Maybe it will do no better than the 5D in this regard. (I was hoping the 7D would be rated at -1.0ev like the 1DIII and 1DsIII, but it isn't).


Quote Originally Posted by Feanor
If I were to swap for the 7D, however, I'd be able to use the 400mm f5.6 and have more reach than the 500mm

Too bad Canon doesn't make long slow lenses. If you're satisfied with a 400mm f/5.6 on a crop body, that would be equivalent to a 640mm f/9 lens on a full frame body. Other things being equal, a 640mm f/9 lens should be easier to make. (But of course, other things are not equal).


I wouldn't switch my 5DII for a 7D unless I was very heavily in to taking pictures of stuff that moves quickly, and even then I'd want to know more than I do now about the 7D. On the other hand, if that was what I wanted, I'd probably get a 1DIII. (On the other other hand, according to some ways of thinking, this camera has less reach than either the 5DII or the 7D).


Jon.