I suppose you are wondering what this is. I got to thinking about dust on the sensor last night and decided to check out our 3 SLR bodies for dust this mornning. This is the image of dust on the 5D sensor. I thought I had noticed some things in a few photos, and sure enough there was some stuff there. A gentle shot of a teensy bit of canned air, and the big stuff all disappeared. Thankfully. The Rebel XT and 5D Mk2 were essentially clean. Ok, enough camera maintenance for today.