Orthochromatic films were first produced by Hermann Wilhelm Vogel in 1873 by adding small amounts of certain aniline-based dyes to photographic emulsions, which until that time had been sensitive to blue light only.
In 1873, Hermann Wilhelm Vogel pioneered the creation of orthochromatic films by adding tiny amounts of certain dye molecules to photographic emulsions. These emulsions were previously limited in their sensitivity to blue light.