I am shooting some portraits for a friend and was wondering if anyone had any advice on shooting with this lens. I'm worried that it will be too hard to focus accurately (on Canon) without resorting to live view. Anyone have any advice on using this lens? Or is it really only for staged stuff? I'm also considering the 50mm f1.8, but it has poor bokeh and mine is a bit soft. Or the 70-200mm f2.8. I will probably go with the zoom, but the extra speed would be nice... Anyone have any advice (on lenses or in general) for a novice at shooting portraits? Hopefully will shoot outside and rely on backlight.