"A little past eccentric" is a phrase that can apply to any of a number of great artists, and when an interviewee uses it describe the title subject of John Maloof and Charlie Siskel's documentary Finding Vivian Maier, it borders on understatement. Maier was a mid-20th century nanny who was also a compulsive photographer, taking upwards of 150,000 pictures of mostly urban life with her stealthy Rolleiflex camera. She didn't develop all the film, and she kept the developed pictures to herself, leading to an obscurity which finally ended when co-director Maloof bought some of her negatives on a whim at an auction. Finding Vivian Maier follows the faux-hawked Maloof as he speaks to the people who knew her as a nanny (including Phil Donahue!), developing a portrait of a shy, emotionally troubled woman who likely would have been horrified by her posthumous celebrity. The selected photos are of course uniformly gorgeous, including many of what we now called "selfies," and a particular anecdote is deeply telling: One time, when one of her charges got hurt, Maier started taking pictures rather than helping the child. We see these pictures, taken decades before the current moral panic about smartphones. No matter the technology, human nature does not change, and Vivian Maier was as human as they come.