Very unique addition to anyone's Army Air Force collection. Here's some detail about the Fairchild K-17. It was a Reconnaissance and Mapping Camera with between-the-lens shutter camera for vertical and oblique aerial photos, using 9 1/2" wide roll film for 9" x 9" images, with exchangeable cones with Bausch and Lomb Metrogon lens of 6", 12" and 24" focal length [1].