Camera uncovers new art secrets, scientist claims
August 11, 2009
Page 1: Scientist claims fresh proof that artists used optics
Picture: An optical scientist says he has found fresh evidence that lenses were used to help 16th century artist, Lorenzo Lotto, paint (Image, courtesy Charles Falco)
A leading scientist has converted a standard DSLR camera to reveal what he claims is fresh evidence that a 16th century artist used optical projections to help him paint.
Amateur Photographer (AP) has learnt that Charles Falco, professor of Optical Sciences at the University of Arizona, modified his Canon EOS 30D to enable it to capture infrared (IR) images of a 1543 painting by Italian artist Lorenzo Lotto.
‘This camera allowed me to extract information on the underdrawings of a number of paintings,’ said Falco who explained that IR light can penetrate further into pigment than visible light, revealing unseen sketches, as well as defects in the canvas or board underneath the paint surface.
Falco said his findings will enable non-specialists to obtain high resolution IR ‘reflectograms’ of artworks ‘in situ’ in a museum environment, using a commercially available camera.
He claims that such a modification makes IR technology available to museums at a ‘small fraction of the cost’ of the 10kg specialist camera that museums currently use for such work.
Falco, a keen photographer, revealed to AP: ‘Very few paintings, including this one, have ever been studied with specialist IR-modified cameras.’
In his recently published Review of Scientific Instruments paper he wrote: ‘Unfortunately, its cost of over $50,000 restricts the number of institutions that can afford it and thus the number of works of art that can be studied.’
Giving museums cheaper access to such technology may lead to more widespread examination of the work of Renaissance artists and the claims published in David Hockney’s 2001 book, Secret Knowledge.
Optical projection theory
Falco collaborated with Hockney for the book which controversially suggested that some artists produced certain features in some paintings with the aid of optical projections, as early as 1430.
In his newly published paper, Falco says that his modified camera has enabled him to conduct a more detailed analysis of an octagonal pattern that appears in Lotto’s painting (see centre left of the above non-IR photo).
Previous research claimed to show that the pattern appeared to go out of focus the further away it is from the viewer – suggesting the artist had copied the detail from an optical projection.
‘Consistent with tracing’
From his latest research Falco asserts that the red and yellow pigments in the pattern are largely transparent in the IR image, bringing into view clear black lines that are ‘consistent with tracing’.
He adds that the lines become ‘tentative’ where – as previous research suggested – the magnification was reduced due to the artist ‘refocusing’ the lens.
Falco said that these new results, combined with those from his previous analysis, provide important new insights into the actual working practices of the artist, revealing details about how he made use of projected images many years prior to the time of Galileo.
To see what the IR image revealed click on the NEXT PAGE
Page 2: Camera reveals unseen drawings
The camera has also been used to uncover additional, previously unknown, drawings underneath Lotto’s painting (pictured in the b&w image below).
‘The IR is an HDR [High Dynamic Range] image I created using Photomatrix Pro 3.1 [software] on three raw images each spaced two stops apart,’ Falco told AP.
‘Two things clearly revealed in this IR is the appearance of a signature-like pattern in the upper centre, and an extra fold of cloth flowing off the table to the right,’ Falco told AP (see top of b&w image below).
‘All the features revealed in the infrared images are not seen in the corresponding visible images and were never previously known.’
Falco explained that, although the dynamic range of a painting is small enough not to require the use of HDR, the ability to enhance contrast on a small scale using a program like Photomatrix is a ‘significant advantage in revealing features, such as the texture of the canvas, in the images’.
Falco’s paper states that he will explore details of Lotto’s ‘working technique’, with Hockney, in a future publication.
Modifications to the 30D included replacing the low pass filter on the camera’s CMOS imaging sensor, with a ‘high pass one’.
‘To be useful to IR reflectometry this IR must reach the detector and… all visible light must be blocked,’ explained Falco.
Hockney and Falco’s theory, as published in Secret Knowledge, was not without its sceptics.
After its publication, Christopher Tyler, associate director at the Smith-Kettlewell Eye Research Institute in San Francisco said that the patch of blur in the tapestry [as explained on Page One of this article] made a ‘weak case for the widespread use of optics’. Tyler added: ‘Even if Lotto has used optical projection, this isolated piece of evidence would not support its widespread use.’
The b&w image below shows the 1543 painting by Lorenzo Lotto. Falco says the infrared modification has uncovered a previously unseen signature and an extra fold in the cloth that the artist did not include in his painting
Pictures: Courtesy, Charles Falco