The Sphearogon family is basically a series of prototypes, embracing a series of different focal lengths and evolving in the pre-war era 1935-1936. They were aimed yo aerial photography and survey. A 180° and more capable lens could be used in ground photography even flying under the radars. we have designs from 16mm to 190 Very few arrived in our days.
This one is 19mm f8 the only one that was made in more than a single prototype and perhaps seen real use.
A very special thank goes to my friend Marco Cavina for all the knowledge he shared with me about these early lenses.