When I bought my Tamron 17-50, it came with a Kenko UV (0) 67mm filter. It looks really similar to the Hoya green-label filters, but it says on the Kenko package that it's "Double face coated". Is this a decent filter or should I replace it? If i should replace it, what should I replace it with. It's the same one as this one http://cgi.ebay.com/Japan-67mm-Kenk...7QQihZ013QQcategoryZ30066QQrdZ1QQcmdZViewItem Help me out, i'm new to this.