I have had my Canon xsi for almost 2 years now. When I first got my camera my images were very sharp, but as I have used it they are more soft than they used to be. Is it possible for something to go progressively wrong with a camera? I did start out with auto at the very beginning but I switched to AV mode for most of my shots pretty early on. It seems like the more I am learning about settings and how to shoot the worse my pictures are getting. Any suggestions?