Schneider 5 x 5" Combination 85 Color Conversion/True-Polarizing Glass filter
The Schneider True-Polarizing Filter is by far the most effective polarizer for motion picture and television cameras. Having an extinction ratio of ER 374, the Schneider True-Pol is 12- times more effective than other polarizing filters, and is unmatched in its ability.
The polarizing film in a Schneider True-Pol filter is laminated between two pieces of Schneider's crystal-clear, water-white optical glass. The filter is protected against edge-chipping and delamination by Schneider's unique Edge Seal, which also effectively reduces edge-reflections and flare.
The absolute clarity of the glass combined with advanced polarizing material make True-Pol filters particularly effective on demanding scenes, as when shooting through windshields in rigged-cars. On such shots, Directors of Photography have found that Schneider True-Pol filters capture more color saturation, wider tonal range and much more contrast inside the car.
The Schneider 85 Series will produce natural colors when shooting with tungsten film outdoors.
What do you do when you must take some photos outdoors and all you have left is tungsten film? Using tungsten film in daylight will produce a bluish cast in the photograph. The 85 series of filters will "bring back", i.e. color balance the tones in your images. These yellow filters are used to correct differences in color temperature between the recording medium (film/video) and the light source.
It should be noted that an 85 filter produces slightly cooler results than an 85B (with tungsten film in daylight) whereas an 85B converts tungsten film to daylight. The 85C produces the coolest results - more than either the 85 or 85B. However, it is interesting to remember that an 85C is also useful as a creative warming filter with daylight film in daylight.