All, I am seeking opinions regarding the use of skylight filters on a digital SLR. Pros: - They keep junk off the lens - The metal ring provides protection as well Cons: - Good ones are costly - A friend once dropped a camera, had the filter shatter and scratch the lens. He since swore off filters, but uses a ring - They can potentially introduce optical problems Your thoughts? p.s. I have purchased some decent lenses - they all cost >$500 apiece.