Merry Christmas to all of you!
My new (about 2 month) K7 has about 3 stains in a superficial investigation
. I saw one on a clear sky, unusual for dust because of the perfect circular form. Then I read about this problem on K5 sensor. I opened this thread to investigate more, about K7 senzor (and, why not, about the other camera of you and me). I can show only my K7 and Samsung GX20 (K20 equivalent) conclusions in a few days. Using macro FA 100mm/2.8 W.R. at f>8 and very short, unfocused, distance had reveled to me any dust on the senzor in the past, very clear.