The Leica filters for the Leica M system are made of optically pure glass, parallel plane ground and precisely annealed, so the full performance of the Leica M lenses is retained even with a filter attached. The range is purposely limited to the filters most commonly needed in photographic practice: The circular polarization filter eliminates disturbing reflections on non-metallic surfaces, and helps to increase contrast as well as provide richer color reproduction.
