Most of the photographs were taken with a 35mm single lens reflex camera using Kodak High Speed Infrared Black & White Print Film (135-36 HIE 169 2086) and a Wratten Gelatin Filter No. 25 (red) . This filter allowed only red and infrared light to expose the film. The infrared film was tank processed in undiluted D-76 developer and the prints were made on Agfa paper.