It never fails, dust finds it's way to your lens. Unfortunately, some interesting dust has found its way to mine, but not in an easy to access area. I'm using a Canon EF 28 - 135mm and have some dust that has settled -behind- the outermost lens element, as well as one of the more inner ones, as I can see it travel back into the lens when I twist the zoom. Anyone have any suggestions? My thought is I'll probably have to get it professionally cleaned, but I'm all about saving some money if I can. I'm not even sure -how- it got in there, to be completely honest. I noticed a small hole around the front of the lens that I assumed was for letting out moisture when a drastic temperature change happens. I think this may be my mystery entry point, but anyway, a little feedback from you fine folks would be greatly appreciated. Thanks.