In Military Eyes Franz John used the special perspectival situation of abandoned military bunkers located above San Francisco Bay. To get the desired images, he reduced the size of the observation slits of the cave-like structures, until it became a camera obscura which projected the »military point of view« directly onto the concrete walls of the bunkers. By using a camera at long exposure time these moving images were »engraved« on photographic emulsion.  "Carvings on the wall, sketches, notes and even accidental traces can give information about how generations of soldiers have lived and what they might have perceived. Those traces are also references of collective perception as the point of view throughout the bunkers was standardized by the restricted views from observation slits".