Ken Rockwell's very stimulating reviews have sensitized me to the issue of "Pumper Type Lenses" which change their volumes radically by extending or retracting as their focal lengths are changed. This probably happens to some extent with almost all lenses. Air must enter and leave the lens. Due to sealing of the lenses the air must enter and leave via the camera body. Lenses of the Pumper Type include the 18-200 mm DX, the new 24-120 mm F/4 FX, the 28-300 mm FX, etc. On the D3 Ken notices air puffing out of the camera body near the viewfinder. It presumably enters there too. On my D300 there seems to be very good sealing everywhere except around the pop-up flash, where air must enter and exit. (Once a tiny tick seems to have entered there. I saw it strolling around while pointing the camera directly down while photographing a card. At first I thought that a bug was walking around on the card. A couple double takes later I realized that he was in the camera. He's still there, as far as I know.) The D4 does not seem to have any significant openings for air flow except for a long slot near the hinge for the door which covers the memory card slots. * Are there dust filter systems in such Nikon camera bodies? * Is it looking for trouble to use pumper type lenses outdoors in sometimes dusty locations like Renaissance Festivals? * Is dust collection inside of camera bodies a significant worry? * Does dust which enters camera bodies due to operation of pumper type zooms eventually get sucked into the zoom barrels too? * Is professional cleaning of bodies and zooms to remove dust ingested due to pumper type zoom lenses a know routine service? If so, what does it cost and where should it be done? BOTTOM LINE: When in a dusty environment like a Renaissance Fair will using a pumper type lens like the new 24-120 F/4 to avoid changing lenses gunk up the innards of my new D4 worse than changing trinity family lenses at the Fair? Is this dust entry into the camera body enough of a problem to avoid using a pumper type lens in such an environment?