They subtract out (absorb) all but one or more band(s) of the spectrum. Same as a glass of punch. The absorbed energy goes into raising the potentials of the electrons surrounding atoms in the solution and eventually into heat (usually) or radiance outside the spectrum. Regards, Bob... --------------------------------------------------- "Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin ----- Original Message ----- From: "Gregory Fraser" <Gregory.Fraser@pwgsc.gc.ca> To: "List for Photo/Imaging Educators - Professionals - Students" <photoforum@ase-listmail.rit.edu> Sent: Tuesday, October 22, 2002 7:12 AM Subject: Just how do filters work? > Hi Alan, > > I never thought of that and it sounds like a creative manipulation of film. Film would actually block the image like shooting through a microscopic screen wouldn't it? Is that the way filters work? I know they prevent the passage of light but just exactly how do they do it? Is it a wavelength interference voodoo or is it just tiny bits of opaque material in the glass? > > Greg > > > -----Original Message----- > > From: Alan Zinn [mailto:azinn@netbox.com] > > > > Greg, > > I may have some tinted plex you can have. Is this > > transparency film? Could > > you somehow expose a sheet to get a neutral tinted material? I know, > > off-the-wall...! > >
