The K-20 camera is a lightweight, handheld, aerial camera used by the US Army Air Force for oblique photography during World War II (between 1941 and 1946) .
The K-20 was made under contract for the military during WWII by Graflex and several other companies. 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. The lenses were non interchangeable 6 3/8" f/4.5 adjustable diaphragm made by Kodak, Ilex, or Bausch & Lomb, depending on what was available at time of order.
After WWII many of the K-20 cameras were destroyed so that the market would not be flooded with the cameras after the war had ended and they were sold to the civilian market.