Hi, for cleaning the lens of dust, issit advisable to use a camera-cleaning brush or an airblower? I heard some people told me using the brush is not advisable as it may leave smears or scatches on the lens element. I am currently using a Giotto brush made of goat-hair, the brush is supposed to be very soft. Should I get an airblower? What type is good? Any brands in particular to recommend? Thanks..