I was not sure where to ask about this, but it probably applies to anything with a camera lens. A few days ago, I picked up my old Mustek MDC-5000 digital camera (3.1MP, and 5.0MP hardware enhanced) and noticed that every photo taken had 5 or 6 dark spots always in the same locations. After googling a bit, the explanation was dust somewhere in the internal lens. I took the camera apart, and found out that a square piece of blue transparent plastic has mysterious "internal bubbles" that I'm not able to remove. All the pieces included in the lens part are: CCD -> blue transparent plastic -> small lens -> piece of plastic with a hole smaller than the lens (fixed aperture?) -> another small lens. Does this blue piece of plastic have a special feature like filtering some kind of light/colors, or can it be replaced with another "normal" piece of clear or blue transparent plastic?