I have a Canon SD450 and when I take night shots, I sometimes get these blurred spots on my pictures. It looks like dust got into my camera through the small crevices and through the retractable lens and is only noticeable while taking night shots. Day shots I guess there's enough light to drown out the dust. The dust is not on the external lens...I've cleaned it with a dust cloth and it's spotless but the spots still appear. Is there a way to blow/suck out the dust from the internal side of the lens?