Actually, the sensor in any DSLR is covered by a thin filter to protect it, but it tends to attract dust and debris since its electrostatically charged. I managed to get rid of some trouble spots by using the Lens Pen, a bit of a brave move on my part but it worked.
So, away @ f/16 we go for more macro shots.
I just need to learn how to get this right, it's a low-percentage exercise.
I managed to get a few decent files, today, maybe I'll fare better next time around.........