Formatt Hitech 3 x 3" 81B Color Conversion Filter

The Formatt 3 x 3" 81B Color Conversion Filter controls the bluish coloration that affects daylight film. They can also remove excessive blue from the effects of electronic flash.

It's Autumn. The clouds are low hanging and the sky is "patchy blue". You've gone for a ride upstate to the mountains and the light in open shade is bluish. A photo taken of your girlfriend with daylight balanced film leaning against the side of a barn will yield bluish tones that she might not find particularly flattering.