Yea, I think the Sigma is pretty soft at tele ends, but maybe its my shooting techniques that cause it too. Anyway, my doubt is that why would people buy a 70-300mm lens when a 28-300mm lens is available too from Sigma or any other brands. I thought it would be better to have a 28-300mm lens since this would mean that the person can bring out one less lens, say the kit lens, which cover 18-70mm (minus the wide end, unless wide angle is really needed).