The Hitech 100 x 100mm Black and White Filter Kit is a set of 4 commonly used filters for black and white photography. Included in the kit are a #8 yellow filter, a #11 yellow-green filter, a #21 orange filter, and a #25 red filter.
The #8 yellow filter slightly darkens skies, helps to cut through haze, and improves overall contrast. It is the most common contrast filter for black and white photography, producing an accurate tonal range and compensating for the blue sensitivity of panchromatic film. There is a 2x filter factor with this filter, requiring an increase of 1 stop for normal exposure.
The #11 yellow-green filter subtly darkens skies and lightens foliage. It is commonly associated for use with portraiture and attaining greater separation from skin tones and outdoor backgrounds. There is a 2x filter factor with this filter, requiring an increase of 1 stop for normal exposure.
The #21 orange filter noticeably darkens skies, helps to cut through haze, and improves overall contrast. When compared to the dark yellow #15 filter, the #21 creates an even greater separation between clouds and sky and further lightens yellows and reds within the scene. There is a 4x filter factor with this filter, requiring an increase of 2 stops for normal exposure.
The #25 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.
These filters measure 3.9 x 3.9" / 100 x 100mm and are compatible with the Cokin Z-Pro filter holder. They are constructed out of CR-39 dyed resin.