I photographed a set of paintings for an artist that worked out quite well by doing it outside on a bright, sunny day, the paintings flat on the ground on a large sheet of cardboard painted black, with a large white sheet overhead on a couple of poles to diffuse the sunlight. I shot straight down from a staircase with an overhang, and the sun was a a slight angle as it was at about 3 in the afternoon, so shadows from me and the staircase were not a problem.
Your problem will be finding a suitable staircase, or some other method of getting up high enough to be able to shoot the whole canvas. How large are the paintings, and do you have a good wide angle lens (I used my 24mm, and was careful to align the film back in the same plane as the canvas)? Flash is out of the question, unless you have several very large diffused panels. Good luck; its tricky, and you may have to correct the perspective once they are scanned in. Cameron Hood
