Stopped down to f/7.1 at around 105mm, the 70-200 Canon lens is very sharp,and has ample depth of field for a half-body shot at indoor distances,and gives a bit of a safety margin on focus. Focusing under the modelling lights from my Speedotron system is not always "100%" with the 5D; the light level under the modelling lamps is simply not "that" high,and the 5D is not as good of an AF camera as say, the D2x is,under the same studio lights.