?-1580

German mathematician who first suggested the idea of a portable camera obscura. The latter is a dark chamber, used for experiments in optics and generally considered to be a precursor to the modern camera. In 1572, Risner suggested that rather than a darkened room, a wooden hut would make a more useful camera obscura since it could be moved. He also edited a highly influential edition of writings by Alhazen (965-1039) and Witelo (c. 1230-c. 1275) on optics.