The red separation negative was exposed onto panchromatic film through the red unsharp mask. A 1920s technology using special panchromatic film with a lenticular layer behind the emulsion. Photographs of the lunar near side and far side were obtained with panchromatic film. Panchromatic film renders all colors in shades of gray approximately matching their subjective brightness. One records the color red (via a dyed panchromatic film), and the other, blue (orthochromatic). This was an extremely fine-grained, high-contrast, extended-red-sensitivity panchromatic film that benefited dramatically from hypersensitization.