I'm doing a favour for a friend of mine who is a painter: I'm supposed to photograph a few of his oil paintings, not for large format reproduction, but for relatively small images to go in a catalogue. [Note: this is not a professional engagement.] Now, when shooting, sunlight will not be an option, and I know hot lights introduce unwanted colour (and, I guess, might cause harm to the artwork on account of the heat emitted), so my question is: are there any objections to using flash in this scenario? I'm thinking two strobes armed with shoot-through umbrellas, aimed at the canvas surface from 30-45 degrees from each side. What are your thoughts on this? Thanks!