The sodium vapor process is a filmmaking technique for combining actors and background shots. It originated in the British film industry in the late 1950s and was used extensively by Walt Disney Productions in the 1960s and 1970s as a solution before the green screen technology we know today. The filming used sodium vapor lamps in front of which the shots were shot. A beam-splitter camera is used to expose the two separate elements of the film. The main element is normal color negative film which is insensitive to sodium light and the other a black and white film which is highly sensitive to the specific wavelength produced by sodium vapor. In this way the actors' figures could be combined with a different background and captured with great color accuracy in a final film. Production studio Corridor Digital has released a video showing a modern application of the sodium vapor process, using a custom filter developed by Paul Debevec.