Plus Green is a technique of professional lighting.
Technical Details
Plus Green filters operate with a light transmission of 65-75% and a color temperature shift from typically 5600K to 5200K at +CC40. The films are made of heat-resistant polycarbonate with a maximum temperature resistance of 150°C. Standard versions are 1/4 Plus Green (+CC15), 1/2 Plus Green (+CC30), and Full Plus Green (+CC60). The spectral transmission shows attenuation in the red and blue regions with increased green transmission between 520-570nm.
History & Development
Plus Green developed in the 1970s as a response to the uneven spectral characteristics of early HMI lamps, which exhibited a pronounced green cast. Osram and later LEE Filters standardized the CC values in 1982 for consistent color correction. With the advent of digital cinematography from 2005 onwards, Plus Green gained new significance for matching various LED panels, as these often exhibit spectral gaps in the green range.
Practical Use in Film
On "Mad Max: Fury Road" (2015), DoP John Seale used Plus Green filters on HMI lamps to match desert scenes with practical light sources. A typical workflow: LED panels receive 1/4 Plus Green, while tungsten lamps are combined with 1/2 CTO to achieve identical color values. The filter eliminates the typical magenta cast of cheaper LED systems and creates more natural skin tones. Disadvantage: The light loss of 25-35% requires stronger base lighting.
Comparison & Alternatives
Minus Green acts in the opposite direction and corrects excessive green components from fluorescent tubes or old HMI bulbs. CTO filters only change the color temperature without a green-magenta shift. Modern RGB LED panels offer digital color correction and are increasingly replacing physical filters. However, Plus Green remains indispensable when mixing different light sources, as subsequent color correction in post-production requires complex masks and reduces image quality.