Andy Warhol might be best known as the pop art painter of Campbell’s soup tins and Marilyn Monroe, but his friends remember him as a photographer.

“Andy would carry around this Polaroid camera called the Big Shot. I remember him having to physically move back and forth to get it into focus, but he’d be taking pictures with it all the time,” says Vincent Fremont, a former studio manager at Warhol’s famed Factory complex in downtown New York, who worked closely with the artist from the early 1970s until his death in 1987.