Dick Polak: A 20th Century Boy brings together decades of candid, quietly electric portraits from one of the era’s most trusted backstage observers. Polak, who died earlier this year at 85, captured performers who helped define the cultural weather of the 1960s and 70s: The Rolling Stones, John Lennon, The Faces, The Who, Marc Bolan, Jimmy Cliff and Anita Pallenberg among them.