Debate Over Optics in Early Art Is Focus at OSA Gathering

The controversy over the use of optical aids by early Renaissance painters is cross−disciplinary and emotionally charged.

Did Martha Stewart need to engage in insider trading? Did she engage in insider trading? University of Arizona physicist Charles Falco asks these questions as a way of emphasizing that whether early Renaissance artists needed to use optical aids in their paintings is a separate question from whether they actually did use them.

Stork

This fall, an Optical Society of America meeting in Rochester, New York, brought together Falco, the leading scientific voice supporting Hockney; David Stork, the chief scientist at Ricoh Innovations in Palo Alto, California, and the most vocal scientific opponent; and historians of both art and science. "The last time I saw something as animated as this was [at the American Physical Society meeting in 1987] after the discovery of high−temperature superconductors," says OSA president Peter Knight. "One side wants to believe that artists worked by trickery. The other side thinks it's blasphemy. We spent the rest of the week arguing about it."

Did this artist use optical aids?

"I find the optical evidence overwhelming," says Falco. He points to his calculations using Lorenzo Lotto's 1523−24 painting Husband and Wife. From the painting's 56% magnification—deduced by assuming that the woman's shoulders are of average width—Falco calculates that the artist used a lens or concave mirror with a focal length of 54 cm. Given that, distortions in the perspective of the carpet design can be explained only by the artist's having twice adjusted the lens to bring different parts of the design into focus, he says. "My calculations agree with the measured changes in magnification to within 0.2%." Where the carpet looks fuzzy, he adds, it's outside the lens's depth of field. It's such calculations on geometrical distortions that convince him: "We're not saying that lenses are the only way to get the perspective right," Falco said in his talk in Rochester. "We're saying that lenses are the only way to get the perspective wrong in precisely the way I am showing you they got it wrong." Most of any given painting would have been done by eyeball, he says. "But certain features, perhaps 5% of a painting's surface, was done with the aid of optics; 95% was not."

Stork counters that other explanations for the same distortions are more plausible. For example, studies show all surviving Lotto−like carpets are asymmetric, he says. "Hockney and Falco are fitting noise. It completely undercuts their evidence." Walter Liedtke, a curator at the Metropolitan Museum of Art in New York City, says the distortions in the carpet could come from the painting's canvas having been stretched. And, he stresses, there's no reason to assume the artist was painting everything from life. "Many of the rooms are obviously made up, artistic conventions. The idea that a painting represented an existing room wouldn't have occurred to [art historians]." Stork notes that pinpricks show that Jan van Eyck's 1432 portrait of Cardinal Albergati was magnified mechanically, with a proportional compass. "All the evidence is against [optical aids]," he says. Artists in the early Renaissance "didn't have the knowledge, and they didn't have the materials."

The dispute turns on the state of the art of glass and mirrors. Were the necessary optics knowledge and materials available in the early Renaissance? No, says Harvard University's Sara Schechner, a science historian and curator specializing in early scientific instruments. "I don't think they had any knowledge of image projection from mirrors onto a screen in the 15th century." Even if evidence is found that they did have the knowledge, she adds, "it's not going to change my argument that they didn't have the materials."

But for many meeting attendees, the door was left open by the thriving spectacles−manufacturing business in 15th−century Florence described by University of Massachusetts historian Vincent Ilardi. "The optical knowledge was certainly available. If the manufacturing capability was available, I see no reason why artists would not have been able to project images," says David Lindberg, a University of Wisconsin historian of early optics. At the meeting, he adds, "the acrimony was electric. It was in the air."

Among physicists, the jury is still out. "There was no smoking gun for Falco," says Knight, who left the meeting leaning toward the con arguments. But others, such as John Wood, chief optical engineer for the Hubble Space Telescope, are swayed by the evidence suggesting that early Renaissance painters could have used optical aids. "Falco used basic optics calculations to show focal lengths. It's proceeded like a scientific inquiry," he says. "I think appreciation of art is being advanced with everyone being interested in this."

Liedtke, for his part, allows that Renaissance artists may have used some optical aids, but he says, "for the vast majority of art history, it's a footnote. These questions are irrelevant, trivial, for art historians." Moreover, he adds, the optics claims "depend on very narrow measurements. It all seems so unnecessary. By the time an artist had it all set up, he could have knocked it off freehand. [The optics claims] underestimate the skill of the artists." Referring to a 1420s painting by Robert Campin, for which Hockney and Falco claim optical aids were used in painting latticework on the back of a bench, he adds, "Why don't they step back and think, Why is the bench there anyway? An artist would say it makes a framing device for an important head. Can't people just appreciate the painting?"