Because the tiniest speck of dust in a camera can appear huge on a photograph, Canon has combined a number of technologies, including one that uses ultrasonic vibrations, to keep dust off its latest digital camera.The EOS Digital Rebel XTi single-lens reflex camera, introduced on Thursday, employs what Canon calls the Self Cleaning Sensor Unit. The technology keeps the low pass filter in front of the camera\u2019s sensor clean by using ultrasonic vibrations to shake dust off the surface. The vibrations are activated for one second each time the camera is turned on or off, or via a command in the menu. The dust that shakes loose from the filter falls onto an adhesive strip that captures it, so it won\u2019t float back onto the filter. The EOS Rebel XTi has interchangeable lenses, so dust can easily get trapped inside the body of the camera when users switch lenses. \n\n\n\n\n\n\n\n\n\nEOS Digital Rebel XTiJust in case a speck or two remains, Canon also offers a fallback. Users can activate the dust delete data function, which maps the size and place of any remaining dust. The mapping information is attached as metadata to subsequent photos. Once users transfer the photos to a computer, they can apply a dust delete function\u00a0that subtracts the dust image from the photo.Canon also applies a couple of other simple techniques to reduce the potential for dust to ruin a photo, including treating the filter with an antistatic charge to help prevent dust from sticking to it. Canon also used new materials in the body cap and shutter that are less likely to produce dust particles during use. Canon isn\u2019t the first to apply some of these technologies, but it has combined several of them into one camera. Olympus America and Sony both have their own systems that use vibrations to shake dust off the filter on some of their digital cameras. Third-party companies, such as FotoNation, have developed dust mapping software tools similar to Canon\u2019s dust delete data application. The 10.1-megapixel EOS Digital Rebel XTi will cost US$899, including a zoom lens kit. It will become available in mid-September.-Nancy Gohring, IDG News Service (Dublin Bureau)Related Links:\n\nCanon Claims Smallest, Lightest HD Camcorder\n\nAugust\u2019s Coolest GadgetsCheck out our CIO News Alerts and Tech Informer pages for more updated news coverage.