I use Hoya HD filters because I believe two things:
1. A filter is good protection for the front lens element. After carrying my camera around in the desert for a full day I see what collects on the front of my lens and I don't like it. After smashing a perfectly good Tiffen UV filter (I tripped over my own feet and fell, taking my D5100 with me) and thinking, "Gosh, that could have been my lens..." I took off the now useless Tiffen filter and got on with life none the worse for wear. I now use Hoya HD filters because the HD glass is pretty gosh darn tough. Really tough. They also clean up soooooo easily; fingerprints, dirt, schmutz... It all just wipes off.
2. If you're going to put a filter on your lens, use a filter that serves a purpose besides just protecting your front lens element. Personally I use a Circular Polarizing filter, but that's just a personal choice. I'll plug the Hoya HD CPL again because they also have a much higher light transmission so you only lose about one-stop, versus the typical two-stops you would using another CPL.
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Is this true with the digital clear filters as well?