(under subclass 268) Subject matter includes a filter in front of the photocell to block undesired wavelengths of light.
SEE OR SEARCH THIS CLASS, SUBCLASS:
209, for exposure data derived from film container which controls an optical filter.
241, for exposure filter in exposure control circuit.
SEE OR SEARCH CLASS
352, Optics: Motion Pictures,
212+, for shutters with light-modifying blades including means to alter the color content of light. 359, Optics: Systems (Including Communication) and Elements,
586, 590 for light interference using device with layers of specified refracting index and subclasses 885+ for generic color filters.
