The Hockney documentary mentioned is fascinating. He shows works where the painter has reproduced optical effects (ex: depth of field), conclusively showing tha

The Hockney documentary mentioned is fascinating. He shows works where the painter has reproduced optical effects (ex: depth of field), conclusively showing that a lens must have been used. Wiki has a good article on the topic: https://en.wikipedia.org/wiki/Hockney%E2%80%93Falco_thesis https://en.wikipedia.org/wiki/Hockney%E2%80%93Falco_thesis