I bought a B+W 49mm XS-Pro Clear UV Haze with Multi-Resistant Nano Coating (010M) filter to protect my lens, I decided to forego the lens cap and just use a clear filter and hood ala David Hobby. So...since I've never been a "protective filter" on the lens sort of a guy and that I'm a pixel peeper of the worst kind, I thought I'd do a test to see what kind of image degradation happens with the filter on. I'm happy to report, that I don't see any that is worth talking about. There is a SLIGHT loss in contrast and a SLIGHT loss in sharpness but you have to crop about 400% and zoom to 2:1 to see it so I didn't get upset about it. Here are the crops and for reference the crop size screen shot is below also. The filter is 39.00 on Amazon with 2 day free shipping for prime members.