The Lee Filters 75x75mm Color Temperature Adjustment 81EF Pale Amber/ND 0.9 Filter controls the bluish coloration that affects daylight film. They can also remove excessive blue from the effects of electronic flash. With an 81EF, it is good for general scenics when the photographer wishes to remove the bluish cast from open shade or just add warmth to the photograph. This filter combines an 81EF with a .9 (3 stops) neutral density filter. The Lee resin filters are made from lightweight, optical polymeric materials.