My mom and I (me mostly) have noticed, that on some of my pictures, where the background is very bright, always has shown up, in the blue sky pictures, there will be a dark circular speckle on the top left corner of the picture. It' s not something continuous, it does not show up everytime, and is only with the blue sky shots, where it's bright, or noticable. I thought I might have to return it, if it's a defect in the camera, since I have not had it but two weeks. What could this be? How can I fix it? We already cleaned the lense. I am pretty sure, that there is dust on the sensor, though. I opened up the camera,and looked at the sensor, under bright light, and did not see a thing, not even a speck of dust, and it looks a lot worse, around lower apertures (higher number) perhaps 18-20-22 f/stops, looks very very bad, but the higher the apertures, (lower the number) the better they look. I have a dust blower made for blowign the mirror with, and I used that, and it moved one big particle of dust, but there are still a lot left. What do you fellow photographers do?