Laura Israel’s documentary profiles Robert Frank, the Swiss-born photographer whose work has spanned more than half a century. Even today, in his 90s, he’s clicking away with a digital camera and issuing instructions to the film crew. The film sketches Frank’s career — his groundbreaking 1958 photography book The Americans, which focused on ordinary folks, often captured unaware in public; his technique of scratching text and lines into his prints; and his assorted motion-picture projects, including the infamous 1972 Rolling Stones documentary, Cocksucker Blues. Israel checks in with some colleagues and collaborators, but Frank proves to be a useful guide, sorting through papers, objects and whatnot at his two cheerfully cluttered homes (an old-school loft space in Lower Manhattan and an isolated cottage in Nova Scotia). The doc also touches on the personal — his life story, with its attendant tragedies, and what inspires and irritates him. It can be a bit of a jumble for those unfamiliar with Frank’s work and his milieus, but there’s plenty of interesting material. Certainly it will motivate viewers to seek out (or revisit) Frank’s oeuvre — his work, even decades old, is still sharp and affecting.