Just have a couple quick questions... 1. Is there a rule of sorts when adjusting your shutter speed and aperture? Does picking one influence the other in any way? I'm just wondering if there's a general rule now and how that works. 2. I have a Canon XTI with the normal 18-55mm lens. Should I get a UV filter for it? What other accessories are useful for the lens or my camera? 3. I've heard the Canon Normal EF 50mm f/1.8 II Autofocus Lens is a really good indoor lens. Is that a lens that is worth picking up? I'm going to NYC in a couple days so I'm thinking I might stop by the B&H store. Thanks!