Mark Johnson is an Oscar-winning producer (Rain Man). He was second assistant director on Sorcerer. (That’s not Mr. Johnson in the photo.)
Mark Johnson: “It was a very tough shoot, probably the toughest. It was so physically hard, and Billy was an absolute perfectionist. I was just starting in the business and I had no idea that directors were quite as driven as he. He knew exactly what he wanted and if he didn’t get it, he wouldn’t shoot, so everyone was on their toes.”
From the book Hurricane Billy: The Stormy Life And Films Of William Friedkin by Nat Segaloff.