The B+W 77mm Slim Infrared Blue-Green 489 Filter is an infrared protection filter for use with devices, such as some CCD sensors, which are sensitive to infrared light. This filter suppresses infrared radiation at or greater than 780nm. The green tint causes infrared absorption to begin at 600nm, and, therefore, does slightly weaken long-wave red light. This green hue and 1.2 filter factor are easily corrected for electronically when used for CCD applications.
The lack of front accessory threads and slim design, only 0.12" / 3mm thick, prevent vignetting when used with wide angled lenses as wide as 17mm in 35mm format. The filter is constructed out of brass for durability and features uncoated Schott glass to prevent interference with the infrared protection.