"Our goal was to set up a controlled environment to get the image sensors of digital cameras dirty and test how effective the different cameras' sensor cleaning technologies are. It is well known fact (and it is a bit over dramatized) that digital SLR cameras are very sensitive to the dust particles found in the air. These particles can settle on the image sensor, and will show up on the images as dark spots when the image is taken with a small aperture (high F number). When the aperture is open, the dust is usually not a problem, since the distance between the sensor's surface and the dust is large enough to get the dust out of the focal plane. When the aperture is smaller (usually smaller than F16) the rays of light are parallel to each other, creating shadows to the dust particles. These shadows will show up as clearly on the images."I have recently started thinking about dust removal myself. Not because I can see any blotches in images on my EOS 10D photos but more because I have never cleaned the sensor. The best I have done is cleaned the mirror on the shutter and my lenses so given that I have had my camera for almost 3 years, I think it might be time. It is good to know that using pressurized air to clean dust on the sensor is about as good as self-cleaning systems. Do any of you have any advice in this arena?