Got a lil problem with my canon 17-85mm lens. Whenever I take a photo of a light background, I see little spots all over the place on the pictures. If I use a darker background, it is harder to see the spots but I could make it out if I look carefully enough at the picture. I checked my lens by looking through the view finder but I dont see any spots there. I tried wiping the lens filter and lens itself, and still no luck. Can the spots be inside of the lens. How can I fix that.

