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.
The Heliopan Rollei Bay III Medium Dark Yellow Filter is a basic contrast filter, primarily for use with black and white film, that strongly darkens skies, reduces blues, and increases overall contrast. It is also suitable for some infrared and false color photography and helps to cut atmospheric haze. There is an approximate 3-4x filter factor with this filter, requiring an increase of 1.5 to 2 stops for normal exposure.