It is a pretty amazing lens, one that can give a 24 1.4 II a super close run for the money at 24mm stopped down a little (not one of the three 24-105 I tried were remotely close to giving my 24 1.4 II a run for it's money, not even at f/8-f/11) and, wide open at f/2.8, center frame, easily beat 70-200 f/4 IS at 70mm f/4 center frame and even beat a 70-300L at 70mm f/4 center frame (at the far edges, maybe outer 1/8th or less of the frame, the 70-200/300 do do better at 70mm though it seems).