Sunlight, daylight, incandescent, fluorescent, and other artificial light sources all have color characteristics that vary significantly. Filters give you better images by adjusting for these light variations.
Film and video are rated for a particular color temperature such as that of daylight or tungsten light. Filters are used to correct differences in color temperature between the recording medium and the light source.
85 Series - Using tungsten film in daylight will produce a bluish cast. The 85 Series will produce natural colors when shooting with tungsten film outdoors. For best results use the filter that most accurately matches your film type.
85: Produces slightly cooler results than the 85B
85B: Converts tungsten film to daylight
85C: Useful as creative warming effect with daylight film in daylight
Designed to produce cooler results with tungsten film in daylight than the 85 or 85B