At 10:12 AM 10/22/2002 -0400, you wrote: >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 > oh gee...... that's way out of my depth. I think there are little tiny guys dressed in the prinary colors that group together as needed to block wave lengths or wave at lengths of light - at least that is what I tell students. AZ Build a Lookaround! The Lookaround Book. http://www.panoramacamera.us