Avotius
Some guy
It is Picasso I am thinking about? There were a set of photographs taken by someone who's name completely draws a blank for me at the moment, many pictures of Picasso painting, especially some of him just in his shorts working?
Mostly David Douglas Duncan, I got his book "Photo Nomad" there's a section on photographs of Picasso, his family, his works and yes including that minnatour 'painting' he did using light