If many more filmmakers decide to make documentaries about their famous, difficult fathers, we're going to need a name for them. The dad docs. They include documentaries like The Ballad of Ramblin Jack and My Architect about men who left a big impact on the world but a pretty different impact on their children, and it's the children who are telling the stories, stories as much about their relationships with their fathers as about the men in the titles.

Add to the list the new film by Mark Wexler, Tell Them Who You Are. Who he is is the son of cinematographer Haskell Wexler, the man who shot One Flew Over the Cuckoo's Nest, to pick just one, and directed his own film Medium Cool in 1969. Mark's profile of his cantankerous dad is absorbing, thoughtful, and funny, and it's my favorite of the genre — if a genre is what we have — for several reasons. One is that Haskell is not only still alive but feisty as hell, full of energy and attitude, and still shooting movies, even as he's pushing 80.

The second reason butts right up against the first: by picking up a camera and pointing it at his dad, Mark is daring to step into a world his father knows inside and out. Although Mark is an accomplished photographer and documentarian in his own right, this time it's personal, and Haskell isn't at all sure that he likes the idea. Their relationship is clear from the beginning when Mark tries to interview his father who halts everything to tell him he's going about it all wrong.

But maybe the best thing about Tell Them Who You Are is that Mark includes all of the elements that you'd expect — interviews with his dad, an overview of his career, clips from his movies, and chats with famous people who've worked with him — but in each one he uncovers an idea, a sentiment, that not only links the scene to the movie as a whole but rounds out an overall curiosity about what makes his dad, and dads like him, tick.

For instance, he talks with Michael Douglas who had the difficult job of being Haskell's boss on Cuckoo's Nest. It was his first time producing, and already he was dealing with a domineering cameraman who thought he knew better than everyone else on the set. Douglas tells some fun anecdotes, but he also mentions that Haskell reminded him of his own strong-willed dad, something that Mark seems to find more interesting than the show-biz talk. Mark visits with Jane Fonda who worked with Haskell and is not only a daughter of a famous actor but a famous mother as well, so she's seen things from both sides, in a way.

In each interview, Mark finds a similarity, a parallel, as if he's humming a song about overbearing dads, a poem about men from a certain generation, cut from a certain cloth, and keeping a certain distance from their kids. In a beautiful shot near the end of the movie, Mark asks for Haskell's help as he tries to get a shot of him swimming. He can't quite get the focus right. With a few tips from his dad, he gets the scene, the father swimming toward the camera, the son zooming in closer, until they meet in the middle at the edge of the pool, clear as a bell.

In scenes like these, Tell Them Who You Are radiates dignity, the unusual warmth given off by the frustration of trying to know someone, the honesty and sense of purpose lacking from movies that try too hard for irrelevant emotion. That clearly wouldn't be Mark's style, and it wouldn't be Haskell's either. Mark finally screens the movie for his father, but he thankfully elides his reaction, reducing it to a few seconds that tell us what we need to know. At a screening in Toronto, an audience member asked Mark about why he did this and asked him to comment on his father's response, and again he chose not to say, leaving the moment as just his and his dad's, not because the bond between them is fragile, but because it's real.