The Hockney–Falco thesis is a theory of art history, advanced by artist David Hockney and physicist Charles M. Falco. Both argued that advances in realism and accuracy in the history of Western art since the Renaissance were primarily the result of optical instruments such as the camera obscura, camera lucida, and curved mirrors, rather than solely due to the development of artistic technique and skill. Nineteenth-century artists' use of photography had been well documented.
In a 2001 book, Secret Knowledge: Rediscovering the Lost Techniques of the Old Masters, Hockney analyzed the work of the Old Masters and argued that the level of accuracy represented in their work is impossible to create by "eyeballing it". Since then, Hockney and Falco have produced a number of publications on positive evidence of the use of optical aids, and the historical plausibility of such methods. The hypothesis led to a variety of conferences and heated discussions.
Setup of the 2001 publication
Part of Hockney's work involved collaboration with Charles Falco, a condensed matter physicist and an expert in optics. While the use of optical aids would generally enhance accuracy, Falco calculated the types of distortion that would result from specific optical devices; Hockney and Falco argued that such errors could in fact be found in the work of some of the Old Masters.
Hockney's book prompted intense and sustained debate among artists, art historians, and a wide variety of other scholars. In particular, it has spurred increased interest in the actual methods and techniques of artists among scientists and historians of science, as well as general historians and art historians. The latter have in general reacted unfavorably, interpreting the Hockney–Falco thesis as an accusation that the Old Masters "cheated" and intentionally obscured their methods. Physicist David G. Stork and several co-authors have argued against the Hockney–Falco thesis from a technical standpoint.
Hockney and Falco's theory has already inspired an increase in research regarding the use of optics throughout the history of art. For instance, there was the case of the decade-long research on Rembrandt's works conducted by painter Francis O'Neill. In the published paper he wrote with Sofia Palazzo Corner entitled, Rembrandt's Self-portraits, O'Neill presented recurring themes in the painter's works that serve as evidence in his use of mirrors, particularly, in his self-portraits. These include the use of chiaroscuro, which is a signature of the lighting conditions necessary for projections as well as Rembrandt's off-center gaze in his self-portraits, which - according to O'Neill - indicated that the artist might have been looking at a projection surface off to the side rather than straight onto a flat mirror.
Origins of the thesis
Aaron Scharf's 1968 book Art and Photography, which details evidence of the use of photographs and the camera by painters, is referred to by Hockney in his 1977 painting My Parents (Tate, London) in which his father is depicted attentively reading the volume. Scharf notes in his introduction that in 1568 Daniele Barbaro, the Venetian writer on architecture, recommended the camera obscura as an aid to artists: "By holding the paper steady you can trace the whole perspective outline with a pen, shade it, and delicately colour it from nature." As described in Secret Knowledge, in January 1999 during a visit to the National Gallery, London, Hockney conceived of the idea that optical aids were the key factor in the development of artistic realism. He was struck by the accuracy of portraits by Jean Auguste Dominique Ingres, and became convinced that Ingres had used a camera lucida or similar device. From there, Hockney began looking for signs of the use of optical aids in earlier paintings, creating what he called the Great Wall in his studio by organizing images of great realistic art by time period. What he saw as a sudden rise of realism around 1420, combined with Charles Falco's suggestion that concave mirrors could have been used in that period to project images, was the germ of the Hockney–Falco thesis.
In 2000, Falco and Hockney published an analysis ("Optical Insights into Renaissance Art") of the likely use of concave mirrors in Jan van Eyck's work in Optics & Photonics News, vol. 11. In 2001, Hockney published an extended form of his argument in Secret Knowledge.