Just to warn you guys. The Sigma 50-150 f/2.8 lens has focusing issues in both Nikon and Canon mounts. This is particularly true when you're focusing at short distances e.g., 2 meters (beyond the minimum focusing. It will be wise to wait and see if Sigma issues a firmware update for the lens. Apart from this, the lens is very sharp even at f/2.8 (at least on the Sigma mount).