don't know if this is the place to post but it concerns my equipment. i just noticed a spec of dust when i look trough the viewfinder. it is not on the sensor as it does not appear in the pictures, it is not on the mirror as the burst mode i tried did not clear it off so i guess it is in the viewfinder itself. it's not a real problem since it does not appear on photos but it is annoying nonetheless. any suggestions on how to get rid of it?