in 2010, i sent my A850 for cleaning at SSC and everything's well and fine. Then dust starts to appear in the viewfinder, probably between the pentaprism and the focussing screen. The weird thing is that the number of dust gets more and more as each week past by and so i decided to send it back to SSC. They told me the surface of the pentaprism that is in contact with the focussing screen got scratched and a replacement cost 500+. But that was back in late 2010, so charges might have already increase.