This is gonna creep ALL of you out, I'm sure: I've had a Nikon D100 for 2 years for my product photography (as well as the occasional event shoot and portrait sittings). I was always careful switching lenses but lets' face it, "dust happens". It had accumulated SO much dust in that time that I was spending more time with the clone tool and healing brush than I was with scanned medium and large format film for my product shots. Soooo.... Based on some basic advice from a friend who still handles the camera repairs at a shop I used to work for, I turned the camera on, activated mirror lockup, and fired the shutter on bulb - holding the shutter release down to be continually open with the filter and CMOS sensor exposed, and shot canned air in there (couple of short bursts - otherwise you might get a "squirt" of liquid coming from the compressed air). About 90 percent of it is gone! Still have to spend a bit of time in Photoshop correcting it, but it's a LOT better now. Going to have it professionally cleaned as soon as I think I'll have a break in shooting, or can get another body to use in the down time. -Lew ;-)