The K-20 is an aerial camera used during World War II. Fairchild design, made under licence for military contract. Approximately 15,000 were manufactured by Folmer Graflex Corp. in Rochester, NY between 1941-1945. They use a 5.25"x20 to 5.25"x200 foot Roll Film, with an image size of 4x5 inches. Lenses were 6 3/8" f/4.5 adjustable diaphragm, non interchangeable, made by either Kodak, Ilex, or Bausch & Lomb, as available at time of order. An interesting feature is the use of a vacuum to keep the film flat.
Earlier aerial cameras, from the World War I era, included the Kodak K1, with focal plane shutter, the Fairchild K3, K3A, K3B etc., with in-lens shutter to eliminate distortion, K5 etc., some of which used individual glass plates, some individual sheet film, and some roll film.
Similar cameras, from the World War II era: K17, K18, K19, K21, K22, F20, F40, F56, etc., many making 9" x 9" or 9" x 18" images using 9"+ roll film. [1]
Aerial photo histories: