The Hitech 6 x 6" #25 Red Filter is 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 #21 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. This filter measures 6 x 6" / 152.4 x 152.4mm and is constructed from specially dyed CR-39 resin.
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.