It's not air. Air is molecules and atoms made up of the same beasties (electrons, protons, and neutrons) as the filters that started this discussion. It may well be nothing. It may well be something. What ever it is, it doesn't make a good subject for a photograph. Doug Stanley -----Original Message----- From: owner-photoforum@listserver.isc.rit.edu [mailto:owner-photoforum@listserver.isc.rit.edu]On Behalf Of Peeter Vissak Sent: Saturday, October 26, 2002 8:11 AM To: List for Photo/Imaging Educators - Professionals - Students Subject: RE: filters and a long standing question >. . . unbelievably small beasties called neutron and protons >(which may be even incredibly smaller other beasties, but that is another >story) surrounded by very fast moving, also incredibly small, beasties >called electrons. . . Would someone tell me, once and forever, what's there inbetween? Air or what? PV (Tongueincheek Studio)