I felt that I noticed a drop in IQ with a B+W UV filter, so I took mine off and I keep it for harsh conditions (sailing trips, shoots in the rain, etc.). I think LensRentals did a comparison once between the cost of putting a filter on every lens vs. the cost of front element repairs; front element repairs were noticeably cheaper averaged out on a per-lens basis (they have a great sample size in this case). Then I read their blog post, http://www.lensrentals.com/blog/2011...th-bad-filters, and decided I'd leave those filters on the shelf except when I needed them for sealing purposes in harsh conditions. Just my $0.02 of course.