|This is a major nonissue for me (wasn't this already pretty well established with out the Hockney band name) but the newyorker listings dept provides this web address for add'l info about a conference on the subject.
Here's what the conference is about:
"Most art historians believe the majority of European painters since the Italian Renaissance deployed elaborate systems of mathematical perspective to achieve their effects. Over the past several years, however, Hockney and Falco have been arguing that, on the contrary, most artists in the High Tradition, going all the way back to Bruges in the 1420s, were deploying a variety of optical devices (ranging from concave mirrors through lenses and cameras obscura and lucida). In effect they suggest that painters (from Van Eyck through Caravaggio, Lotto, Velazquez, Vermeer, Chardin, Ingres, etc.) were using precursors of photographic cameras for centuries before the invention of chemical fixatives in 1839; and that it was only with the spread of such chemical fixatives that European painters, suddenly disenchanted with the "optical look," began to undertake the critique of photography implicit in impressionism, expressionism and cubism and the rest of the modernist tradition. Needless to say, these claims (up till now mainly advanced in peer-reviewed scientific journals) are highly controversial: if true, they would have far-reaching ramifications upon our understanding of art."
I agree, Bill, that the question of "how early and/or widespread was the use of photographic devices in painting?" isn't a very interesting issue, for reasons I mentioned above. The conference organizers seem to think it's an issue because they see modernist tendencies in painting to be rooted solely in the "critique of photography." If that "critique" had been going on for centuries, then modernism would have to have other causes. Well, of course it had other causes! Many tendencies in art--an interest in relativity and simultaneity, the quasi-religious search for "essences," art-for-art's-sake aestheticism--were also going on in music, theatre, and literature: fields completely unaffected by the invention or non-invention of photography. The only theory of modernism Hockney's upsets is an utterly simplistic (and I'd say wrong) one.