Sorry, for such a basic question. I've been trying to find the answer online, but I'm not sure. I just bought a D40 kit with the 18-55mm f/3.5-5.6 G II ED lens and I've been reading that I should really get a clear UV filter for protecting my lens. I know that it isn't an expensive lens, but I like to take care of stuff none-the-less. So, I see on Nikon's site that I need a 52mm Screw In filter. Lens detail here I then go shopping. I see... $27 for Hoya 52mm UV (Ultra Violet) Super Multi Coated Glass Filter $19 for Hoya 52mm UV (Ultra Violet) Multi Coated Glass Filter But, how do I know that these are screw in filters and it will fit my kit lens? Are they all screw in? Also, I know that these are good for outdoor pics, but do you just leave the filter on even on the indoors, just to protect from dirt, etc? Does it hurt the image indoors? Appreciate the help guys and girls and thanks in advance.