Light that strikes the film plane is measured in 'Wavelength.' Within the wavelength is a 'band width' and each color has a temperature along the band width that effects the photo sensitive material differently. Filters deflect some sensitivity off the wavelength and compress the most into few bands within the wavelength. To use a filter or filter pak lets us control the wavelength, making it even when the light strikes the film plane to make a picture. Ansel expressed his preference to non coated lenses in a letter to Cole when the young Weston was shipping for a lens, at the beginning of his individual career. AA said he wanted to control the wavelength with filter choices of his own, not to rely on the interpretation of the manufacturers' coating. As a student in physics, myself, the teacher began our study of light by asking us to consider: What happens to the light when you turn off the switch before going to bed? S. Shapiro, Carmel ----- Original Message ----- From: "Steve Shapiro" <sgshiya@redshift.com> To: "List for Photo/Imaging Educators - Professionals - Students" <photoforum@ase-listmail.rit.edu> Sent: Thursday, August 15, 2002 1:02 AM Subject: > Re: Light and filters question to ponder > No! > > Why is that a stupid question? Because filters 'filter out' the light. > > S > > Student question: > > >If a filter has a density of .3 and thus lets > > >through only half of the incident light, would > > >all the light eventually pass through the filter? > > >
