>My concern with dust is with fouling the sensor. believe me >when I tell you that sanding a piece of wood on a lathe at >2000 rpm will send clouds of wood dust into the air that would >make you wish you had one of those face masks that they wear >all over Japan. I have to wipe my camera off with a fluffy >brush when I leave the meeting. Unless you need to blow off >your equipment in the areas you cited I think you would >understand my concerns. JB
Also remember that when you zoom on any lens that extends as you do so, you're pumping air, and dust, in and out of the lens and into the mirror box. If you do it quickly, you can even feel it coming out of the eyepiece, so the dust is getting in there anyway. I use primes with dust seals and a NC or UV filters in nasty environments like that to really keep crud out of the camera, and IME it's more effective than leaving a zoom on the body the entire time.