The Heliopan 62mm Green Filter is a basic contrast filter, primarily for use with black and white film, that darkens blue and red tones while lightening green tones. It is especially useful for portraiture and still life applications, as well as outdoor scenes with foliage. There is an approximate 3x filter factor with this filter, requiring an increase of 1.5 stops for normal exposure.The Heliopan 62mm Green Filter is a basic contrast filter, primarily for use with black and white film, that darkens blue and red tones while lightening green tones. It is especially useful for portraiture and still life applications, as well as outdoor scenes with foliage. There is an approximate 3x filter factor with this filter, requiring an increase of 1.5 stops for normal exposure.