I too am irritated by the 1/250th limit in Auto ISO in Av mode. If I'm in Av mode, I should be able to automagically have a shutter speed higher than that and have the ISO go to to whatever it needs. I guess that is a fairly complex thing for a camera to do, but it would still be nice. So, you switch to manual mode. But with auto ISO there, no EC. So if you shoot the 5D Mk III, you really have to do most or all of your exposure compensation via ISO #. Well not really, but you know what I mean.