> 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?
'Tis magic, I tell ya'
Leaping electrons. Diversionary tactics. The wavelengths absorbed are determined by the molecules in the filter having an orbit/level that an electron can jump into when struck by a particular wavelength of light. This is how selected wavelengths are absorbed. Current chemical technology allows designers to exercise fairly precise control over what wavelengths will be absorbed.
It is useful to remember that filters work by susbtraction,
by selectively keeping part of the spectrum and/or volume of incoming light from reaching the film. Color filters work by absorbing
their complimentary colors. Where these absorptions occur, they
leave blank areas in the negative, which reproduce as dark/black
on the print. Most filters do not totally block out their complimentary
colors, but simply attenuate them considerably.
--- Luis
