Schneider 81-One Warming Filter 4x4. Born from the 81-A, both filters are designed to add warmth to skin tones and reduce excessive blue in outdoor open shade. The 81-Two is used to accentuate skin tones for a warmer appearance. For a subject with darker skin tones, the 81-One is more appropriate. Ideal for romantic close-ups, the 81 Series can be combined with softening filters.