(Carl Zeiss Jena) Aerial Hot-Air Balloon Camera

13x18cm, undocumented aerial camera for use from hot-air balloons with a built-in clock and altimeter, these were photographed by stereo lenses (with built-in shutter) inside the camera and transfered to the negative (a data back from 1911!), this sophisticated camera built by Carl Zeiss Jena was produced by special order and delieverd to St.Peterburg, Tessar 4.5/21cm no.186444 in Compound shutter, changing magazine, folding finder, cable release, metal plaque with inscription attached on the side