I've just noticed some dust/spots on shots @ f22. It's the same on different lenses so it must be dust on the sensor. I'm not sure what the sensor looks like as when I remove the lens all I see is the mirror. How do I lock the mirror up to clean the sensor (which I assume is under the mirrror)? I can manually lift the mirror and there is a smaller mirror-like part under it, is this the sensor? I've never had this problem since I got the camera in 2007 so I've never tried to clean it. I have just been using the Clean CCD process on the camera. Thanks for any help.