Seventy percent of "Overlord" is "live action" (newly shot footage), shot in 10 days. The rest is archival footage, from British training missions to the invasion itself, as well as captured German film. Cooper and his cinematographer, John Alcott, tried to create a consistent look when filming the contemporary footage. “After Alcott examined pristine nitrate negatives, we decided to film Overlord on period lenses. Alcott scoured England and found two sets of 1936 and 1938 German Goetz (sic) correct spelling is Goerz and Schneider lenses. Alcott then applied a lighting style in keeping with the war photography.”