This is the 77 mm Infrared and UV Blocking Filter (38) from Heliopan. It cuts UV below 300nm and infrared above 800nm. It is designed for use with black and white and color films that are sensitive to certain values of infrared and UV light not visible to the human eye. Using traditional contrast filters such as a yellow 12, red 25 or green 15 will produce a color shift which may not be desired in the final image. Greens may become blue, red becomes green and yellow becomes blue/green and infrared becomes red.
