Thursday, July 14, 2016

Did Rembrandt "Cheat"? Optics Paper Weighs in on Art History Debate

Works of art by masters like Rembrandt may have harnessed the power of light to create awe-inspiring, realistic paintings. This being Physics Buzz, artistic techniques are not really our specialty. However, it’s worth a look at the way that the scientific and artistic side of light merge in an article that just came out in the Journal of Optical Physics, published by the Institute of Physics.

The authors, two independent researchers in the UK, revisit a controversial thesis proposed by artist David Hockney and physicist Charles Falco in 2000. Hockney and Falco say that Renaissance artists likely used optical tools like mirrors and lenses to project images of their subjects onto surfaces. The artists then traced these images or used them as a guide to create more realistic paintings.

The short version of the story is that Hockney and Falco attribute the rise of the more realistic portraits of the 15th century to this technique. This is based on an analysis they did of several Renaissance paintings. These paintings show unusual perspectives or other features that Hockney and Falco interpret as kinds of optical artifacts caused by projection tools. Their claims have been met with a mix of skepticism, critique, and support. Many art historians remain unconvinced.

A leading voice among the skeptics is physicist David G. Stork, whose analysis of the same paintings found that the abnormalities aren’t consistent with the use of optical tools, and who provides seemingly reasonable alternatives. Among others, criticisms of the theory include: the lenses and mirrors manufactured at that time were not good enough for detailed projection, there is no written evidence of this technique or depictions of projection setups in studios of that time, and that realism is possible without these tools. Much debate ensued and continues.

The authors of the new paper, Francis O’Neill and Sofia Palazza Corner, focus primarily on Rembrandt’s self-portraits. These self-portraits are consistent in lighting, focus, size, and perspective with the use of projection, they say. In addition, they lay out a case based on 17th century literature that Rembrandt would likely have known about advanced optical techniques and had access to some of the cutting-edge lenses and mirrors of his time. Simple arrangements of these tools would have enabled an artist to be both subject and painter.

A self-portrait in an age with no photography means that the artist either relies on memory or holds a pose while looking back and forth from a mirror to the canvas. Challenging at best, this is much more difficult when the artist is painting a portrait of himself laughing or with his eyes wide open according to the authors—as in two of Rembrandt’s famous self-portraits.

Rembrandt Laughing. Image Credit: J. Paul Getty Museum, Los Angeles. Public Domain (PD-Art).

Another piece of evidence they refer to is his off-center eye focus. If you look at yourself in a mirror, your eyes are looking straight ahead. If you look at an image of yourself being projected onto your work surface, your eyes are looking off to the side because you’re not looking into the mirror. You can see this off-center eye focus in several of Rembrandt’s early self-portraits, say the authors.

The paper offers several other observations of Rembrandt’s self-portraits in support of this hypothesis, such as his choice of medium in early etches (copper, which shows projection contrast well), the increase in size of his self-portraits over time, a loss of detail in areas that may have been outside of the projected image or impossible to project, consistent head sizes in later self-portraits even when the portraits were different sizes, and his carefree style.

Although the researchers don’t address all of the arguments proposed by Hockey and Falco and refuted by Stork, they do say that similar evidence of optical tools can be found in self-portraits by Renaissance artists and that this was probably a common technique. They also suggest that Rembrandt’s use of projection went beyond self-portraits, although that is not the focus of the paper.

Although it may be the most dramatic, the ongoing debate is not alone among work at the intersection of physics and art history. In recent years physicists and art historians have explored the fluid dynamics behind the “accidental painting” technique of David Alfaro Siqueiros, uncovered the signature of Francisco Goya on a painting using terahertz imaging, and much more. This topic seems to have a lot more at stake though, as many people would view the use of projection by the old masters as cheating. Hockney, Falco, and Stork would disagree with that sentiment, but that point seems to be lost in most of the discussions. Interested in learning more? You can read the paper here.

Kendra Redmond

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