By Josh Jacobs

Upon first glance, Nancy Buirski’s “By Sidney Lumet” appears to be a retrospective. With footage of Lumet discussing all of his films from a previously unseen 2008 interview with the director, who died in 2011, the documentary feels like a master class with a director in an art gallery, carefully self-curated.

It would have been easy for Buirski to leave her documentary as such: a retrospective in memoriam to Lumet, who made movies such as “12 Angry Men,” “Serpico,” “Dog Day Afternoon,” “Network” and “The Verdict” and left an indelible mark on the film industry regardless of its constant state of flux.

What Buirski does, however, is take everything Lumet says — about his own life and history and about his films — and pair it with his films, resulting in a conversation between art and artist that paints a self-portrait of Lumet.

While at times remaining on Lumet too long, causing the documentary to drag with nothing visually arresting to see, Buirski remains steady in her pursuit of a final picture of who Lumet was as a person and a director.

Near the film’s end, Lumet discusses “A View From the Bridge” and how he wasn’t sure how he felt about Detective Cello as a character. He didn’t know what he made of him until, he says, “oh, I made him a hero.”

Buirski places Lumet’s audio of “Oh, I made him a hero” over a close-up of Detective Cello, then cuts to a conversation from “The Verdict” about the pursuit of goodness, of truth and right.

In that moment, it becomes clear that Buirski is guiding Lumet’s voice. She doesn’t insert herself into the documentary, choosing to give Lumet the space to breathe on his own, but slowly guides the course of his self-portrait into a painting of Lumet as a hero. Buirski allows this documentary to be a celebration of Sidney Lumet by Sidney Lumet.