The Heliopan 82mm Dark Red Filter is a basic contrast filter, primarily for use with black and white film, that completely absorbs blue and green tones, enhances reds, cuts through haze, and increases contrast for outdoor photography. It is suitable for use in tri-color separations and for photographing faded documents. There is an approximate 8-12x filter factor with this filter, requiring an increase of 3 to 3.5 stops for normal exposure. Same as (25) except with a more pronounced effect.
Single coatings on both the front and rear offer protection to the glass and help to improve light transmission and image quality.
Constructed from Schott glass for optical clarity.
Brass filter ring helps to prevent jamming and provides additional strength.