I Just bought the Sigma 70-200mm f/2.8 DG MACRO HSM-II lens from B&H for my Nikon D300. I'd like to get advice regarding evaluating this lens. Is it good, or should it be RMA-ed for another copy? Sadly, I don't have a full frame body so I can't evaluate performance at the edges. What I have tried to evaluate is general sharpness. Below I have an image showing 6 test shots I took at 3 apertures and the ends of the focal length range. I'd like help interpreting these results. I took these images using a tripod and shutter timer to minimize vibration blur. I shot at 2 distances from the target in an effort to keep the image scale roughly constant across the 2 focal lengths. What these results clearly show is softness at the wide (2.8) end with worse softness at 200mm than 70mm. From reading lens reviews at B&H I see it isn't unusual for lenses to be exchanged for reasons of softness at the wide aperture end ... does this look like a lens that should be exchanged? I realize that some degree of softening is probably common at wider apertures and longer focal lengths and if this is true, the question I face is whether the degree of softening I see is more than I should expect for this lens. Obviously, this isn't a very high-end lens so it would be unreasonable to expect perfect performance but on the other hand, this is no kit lens either. What do you think? Good ... bad ... average? Thanks in advance.