Art history, optics and scientific debate

Our Chief Scientist, David Stork, has been doing some side research the past few years in art history. In particular he’s been assessing a theory that artist David Hockney presents in his book “Secret Knowledge”: that artists as early as 1430 have secretly used optical devices such as mirrors and lenses to help them create their almost photo-realistic paintings.

The theory is fascinating. Art historians know that some master’s used optical devices in the 1600’s, but Hockney and his collaborator Physicist Charles Falco claim that as early as 1430 the masters of the day used concave mirrors to project the image of a subject onto their canvas. The artist would then trace the inverted image. This alone, Hockney and his supporters claim, can account for the perfect perspective and “opticality” of paintings that suddenly appear at in this time period.

If the theory itself is fascinating, I find Stork’s refutation even more interesting. Stork’s argument is based on several points. First, he argues, there is no textual evidence that artists ever used such devices. Hockney and his supporters counter that the information was of course kept as a closely guarded trade secret, and that is why there was no description of it. It isn’t clear how these masters also kept the powerful patrons whose portraits they were painting from discussing their secret. Stork’s second argument is that, quite simply, the paintings aren’t all that perfect perspective after all. They look quite good, obviously, but if you actually do the geometry on the paintings Hockney presents as perfect you see that supposedly parallel lines don’t meet at a vanishing point as they would in a photograph. And third, Stork points out that the methods Hockney suggests would require huge mirrors to get the focal lengths seen in the suspected paintings: mirrors far far larger than the technology could create at the time.

My analysis is a little unfair to Hockney as I’ve only seen Stork’s presentation, but I must say I’m impressed with his argument. Hockney’s argument is quite media-pathic. It’s a mystery story that wraps history, secrecy, geniuses, modern science and great visuals all in one — no wonder it’s captured people’s attention! Unfortunately, I expect Stork’s right about one of the less fun aspects of the theory. It’s also probably dead wrong.

For those interested, a CBS documentary on Hockney’s theory will be rebroadcast this Sunday, August 3rd, on 60 Minutes.