Sunlight, daylight, incandescent, flourescent, and other artificial light sources all have color characteristics that vary significantly. Filters give you better images by adjusting for these light variations. 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. The 85 filter produces slightly cooler results than the 85B.