When Lynn Picknett and Clive Prince get into the news, as they have recently with their new book, The Masks of Christ: Behind the Lies and Cover-ups about the Life of Jesus, invariably new discussion arises about their proposal that Leonardo da Vinci created the image on the shroud using a medieval proto-camera.
Historian Dan Scavone comments on the Picknett and Prince argument that the image was made using a magic lantern, a simple projector, and light-sensitive chromium salts in an egg white medium.
The argument that history’s proto-photo was a life- sized photo(!) on a fourteen-foot cloth(!) that was a composite(!): double corpse with daubed-on blood and, in separate processes, Leonardo’s own head front and back, is a priori far-fetched. The premise is more demanding of faith than is the authenticity of the Shroud. I am led to ask why Leonardo has left us his self-portrait in red chalk and not his photo, and why he would use another body when Vasari notes that his own physique was near-perfect, and everybody knows his exorbitant vanity.
Scavone also writes:
This question leads the authors to another assertion: Leonardo was a member of a secret society called the Priory of Sion, which esteemed John the Baptist over Jesus. Therefore, the apparent disembodied head visible on the Shroud man was Leonardo’s cipher for the decapitated Baptist. Leonardo’s use of his own photo, they argue, was owing to his inordinate vanity, the same that prompted him to encode his own face in his famous portrait of Mona Lisa, wife of Francesco de Giocondo. This theory was confirmed by Lillian Schwartz of Bell Laboratories and Dr. Digby Quested of London, who discovered that it matched up perfectly with the major lines of Leonardo’s face in the above-mentioned self-portrait at age sixty. Picknett writes “Leonardo was capable of subtly building his own image into that of his masterpieces; if he had done so with the Mona Lisa, why not with the Shroud?”
There is also plenty of evidence from science that demonstrates that this is not a photograph. Were it, it would not produce a 3D image. A photograph contains only reflective light data. It does not contain spatial data.