Hoya Hoyarex 3x3" 81 Color Conversion Polyester Filter

The 81 Series of filters controls the bluish coloration that can affect daylight film. They warm scenes shot on cloudy days. They can also remove excessive blue from the effects of electronic flash. These filters are also good for general scenics when the photographer wishes to remove the bluish cast from open shade or just add warmth to the photograph. The 81 series is available in grades from 81 through 81EF, with 81EF having the warmest effect. .

81 Series Color Conversion Chart

81 decreases color temperature 100 degrees Kelvin

81A decreases color temperature 200 degrees Kelvin

81B decreases color temperature 300 degrees Kelvin

81C decreases color temperature 400 degrees Kelvin

81D decreases color temperature 500 degrees Kelvin

81EF decreases color temperature 700 degrees Kelvin.

This filter is 1.7mm thick.