TheB+W #25 Red (090) Filteris a basic contrast filter, primarily for use with black and white film. This red filter dramatically darkens skies, cuts through haze, and increases overall contrast. When compared to the orange #22 filter, the #25 produces very dark, almost black skies and a surreal contrast between foliage, clouds, and sky. There is an 8x filter factor with this filter, requiring an increase of 3 stops for normal exposure. B+W filters are constructed from high quality Schott glass for increased optical clarity and color fidelity. They feature a brass filter ring for durability as well as jamming prevention. Red contrast filter for black and white film dramatically darkens skies, cuts through haze, and gives greater contrast overall. Provides surreal contrast and results in very dark, almost black skies. Constructed from high quality Schott glass for optical clarity. Brass filter ring helps to prevent jamming and provides additional strength.