Changing Lenses Hey all, I have a question about changing lenses. I am always freaking out about when switching out which lens I have on the camera because I am so nervous about something getting into either the camera or back of the lens itself. I do hold the camera facing down when I switch glass to help prevent dust and stuff from getting into the guts, so do you think I'm stressing to much? I want to enjoy this brand new hobby, so I don't want to be constintantly worried about my gear. I don't yet have a blower to clean inside yet and I, but again, I not sure how fragile those parts are. Also, how well do you think the camera's sensor cleaning/shaking system works? Please help ease my fear that I'm gonna mess up my Canon Rebel XS.