Organized by Istituto e Museo di Storia della Scienza

Outline of Florence talk by David Hockney

Over the last 2 years David Hockney has been researching the use of optical tools by artists - primarily as a device for accurate measurement, but also as model for tonalities and chiaroscuro. His findings are to be published under the title Secret knowledge, rediscovering the lost techniques of the old masters, this autumn.

The quest began with a hunch, following numerous visits to the exhibition "Portraits by Ingres" at the National Gallery, London in January 1999, that Ingres had used a camera lucida, then recently invented, for his portrait drawings. Using this device, David Hockney made more than 300 portrait drawings over the following year and, his curiosity aroused, began to delve further back in time - looking for evidence of optical effects in paintings (which his own practical experience with the camera lucida helped him to identify) and reading widely to unearth accounts of the history of the camera obscura, of its various forms and of the veil of secrecy that, it soon became evident, surrounded the phenomenon of optical projections - secrecy that was essential when a practical tool could be misinterpreted by the church as magic and as heresy.

In his studio Hockney pinned up hundreds of reproductions of paintings, ordered geographically and chronologically, and built a simple camera obscura with a lens and a curtain. Armed with a practical understanding of optical measurement from his camera lucida drawings, it quickly became apparent that the complex folded fabrics, shiny armours, etc. in many Renaissance paintings could only have been delineated by optical means. The advent of this breathtaking realism coincided with the appearance of true individuality in faces and the overall look was identical with the optical look of projections in the camera obscura. This look arrived suddenly, as if from nowhere, in Flanders during the first quarter of the fifteenth century.

The first written accounts of a camera obscura with a lens appear in the mid 16^th century and, although lenses existed before (Van Eyck's Canon Van Der Paele is holding a pair of spectacles) this discrepancy was clearly a weakness in the developing thesis.

A chance remark by Charles Falco, an optical scientist, that a concave mirror has all the optical qualities of a lens - provided a crucial clue as to the method of Campin and Van Eyck. Taking the small window portraits as a model, Hockney found that an image of a subject sitting outside a small window, in the sun, could be projected, upside down but right way round, on the wall next to the window. Convex mirrors were being made, and painted, in Flanders at that time (a concave mirror is the back of a convex mirror) - and the Guild of St. Luke numbered both painters and mirror makers amongst its members. Hockney's subsequent experiments with mirror lens projections confirmed this would be a viable working method which, through a collage of drawings pounced onto a panel, would account for the construction and the spatial effects in the larger compositions of Campin, Van Eyck and the other Flemish masters.

The intense and precise realism of the early Flemish painters strongly suggested a use of optics, and the rediscovery of mirror lens projections confirmed a viable working method. Masaccio, however, remains an enigma. Though his medium, fresco, does not allow the subtle blending of tone that Van Eyck could achieve with oil paint, his faces have the same individuality. Was he also acquainted with the techniques of mirror lens projection - using them, like the Flemish painters, via the intermediate medium of drawing? And, to extend the question further, were Brunelleschi's experiments with perspective founded on optical projections he had seen, and then analysed to invent a formal system of perspective?

In his talk, David Hockney will give a fuller account of his voyage of discovery, illustrated with slides and a demonstration.

David Graves
Assistant to Mr. Hockney