 After earning his stripes on a string of B-movies in the 1930s, he first started making serious inroads as a leading cinematographer in 1940 when he worked for Preston Sturges on "The Great McGinty".Mellor did his best work with directors George Stevens (winning Oscars for two of his films, "A Place in the Sun" in 1951 and "The Diary of Anne Frank" in 1959) and William Wellman ("Westward the Woman", 1951).He also contributed to several Anthony Mann westerns, including "The Naked Spur" in 1953, and a number of MGM musicals.