Roger Deakins – cinematographer to the Coen brothers, Martin Scorsese and Sam Mendes, whose work has earned him 14 Oscar nominations and two wins, five Baftas, a knighthood and a reputation for being the greatest practitioner of his craft alive – is struggling to explain just exactly what he does. “Argh!” he exclaims, when confronted by the question: what is cinematography? “Well, I started off trying to be a still photographer, someone like Don McCullin.