Quote Originally Posted by peety3
LensRentals.com is anti-filter in general, but puts a UV filter on every 17-55 lens.

Well, I have had a UV filter on my 17-55 f/2.8 from the get-go, so that could explain why I never noticed any dust inside the lens. Regardless, as you showed, dust won't degrade picture quality to any noticable degree.