I have seen sample pics of the 8-15mm on crop frame, on both Gordon's reviews and other sites, i like distortion at ends that wide, especially if its crop frame I am using it on.The distortions give me a real sense of scale as Iif I am turing left to right watching a barrel wide angle distortion.All I want to know about is image quality, I have no intention of buying the sigma's 10-20mm lenses nor