SX120 IS Lens

I have been taking what I call very good photos with this camera. No problem there. My questions are not about the image, the lens itself. First, has anyone tried the slip on lens tube that allows use of 52mm filters. With the filter in place, the complete lens tube is fully inclosed allowing it to move freely inside. Looks a little funny, but seems to be a good idea. Other than possible vignetting at the wide end, what else might be a disadvantage to this accessory?

Second, I blew a little bit of dust off of my SX120's lens today and my breath not only fogged the outside of the front lens element, but also another element below it. Of course it all evaporated shortly with the fogged inner element laging behind. If stuff can get inside this lens so easily, should I expect dust early on inside my lens?

Thanks everyone......ebikerman
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Christian Amateur Photographer