With Welles sitting just off-screen, cameraman Gary Graver sticks with Hopper’s bearded face for the duration, and the pair just go at it. The gorgeous black-and-white conversation was one of the many fragments produced for the “Wind” production, much of which takes place over the course of a long party hosted by the Wellesian protagonist and fictional director Jake Hannaford (John Huston). Hopper’s rambling thoughts only made it into a few moments of that posthumous effort, but they take on a new dimension in “Hopper/Welles,” as the camera stays with Hopper while Welles, loosely playing the Huston character off-camera, pushes actor-turned-director to get deep. It would have been fun to see the disheveled Welles at the start of his Falstaff period — his booming, inquisitive voice is one of the most famous in history — but over time, its disembodied presence begins to sound like Hopper’s conscience.

“Hopper/Welles” takes place at a distinctive turning point for both men. In his mid-thirties, Hopper is riding high on the success of his directorial debut “Easy Rider,” a movie that lit the fuse of New Hollywood and would continue to resonate for decades to come. He’s also in the midst of completing his daring experimental follow-up, “The Last Movie,” which would imperil his directing career for good. Welles is at the opposite end of that equation. With his studios days long behind him (his last Hollywood effort, the brilliant noir “Touch of Evil,” came out in 1958), he has amassed a trail of unfinished independent projects across the decades. (“Wind” would become the last of them, though he’d complete the masterful essay film “F for Fake” three years later.) By the time the two sit down together, Welles may be a cynic when it comes to the commercial nature of filmmaking, but he retains convictions about the art form as well as its potential to instigate change in society as a whole. Hopper’s with him on the movie front, but ambivalent about his potential as an activist, despite the hippie bonafides enmeshed in his first movie’s DNA. Welles won’t have any of that. While their discursive exchanges include engrossing tangents on art, celebrity, and sexuality, the core of the conversation centers on Welles demanding that Hopper show more investment in the cultural ramifications of his work, and it’s easy to relate. After all, it’s hard to comprehend how the guy behind one of the most iconoclastic American movies of all time can assert, “I don’t think there’s going to be a revolution in this country that ever wins,” but refuse to voice his political inclinations on the public stage. Welles, a lifelong progressive, can’t stand it. “I want you to rage against something!” he cries. In a hilarious aside to his colleagues, he adds: “Ply him with liquor!”

From a cinematic standpoint, the closest precedent to “Hopper/Welles” might be Shirley Clarke’s masterful “Portrait of Jason,” in which her camera simply lingered on its colorful subject as he grew more intoxicated and emotional. By contrast, “Hopper/Welles” doesn’t build to some kind of grand revelation or dramatic catharsis, which makes it less of a standalone movie than one of the greatest bonus features ever made. But anyone invested in the careers of these two monolithic figures will never tire of hearing them babble on. While “Hopper/Welles” certainly invokes the freewheeling “Other Side of the Wind,” it functions more as a companion piece to “Easy Rider,” as Hopper continues to sort out the nature of its success. He’s baffled by dueling responses to the movie from around the country (the rednecks cheer, the liberals scream “Kill the pigs!”) and has settled into the role of what Welles deems a “reluctant revolutionary.” Hopper claims he wants John Wayne’s right-wing audience, but it’s unclear whether that stems from some inexplicable Trojan-horse potential or the desire to reach the masses on his own terms. Welles can only push his subject so far. At times the movie simply becomes an opportunity to experience the way Welles and Hopper relate to cinema as an international phenomenon. They bond over a mutual disinterest in Antonioni’s “L’Avventura” (Hopper claims to have fallen asleep in it multiple times), debate whether “Last Year at Marienbad” is a personal work, and — in a beguiling passage — whether Native American rituals can feature the same sort of magic found in a Buñuel film. Even decades later, their engaging back-and-forth provides a welcome reminder of the art form’s resilience. Sadly, that doesn’t apply to some of the more dated aspects of the conversation, particularly the sexism that crops up as these two alpha males play off each other. In one of the more troubling asides, Hopper recalls an encounter with a woman who appears to be acting for his camera, until he sets it aside and asks her to strip nude. The filmmaker can’t seem to comprehend why she’d be willing to get naked only when the camera’s rolling, a bizarre and troubling declaration that culminates in a sophomoric beaver joke. (Welles doesn’t exactly emerge from the exchange unscathed, though he at least tries to acknowledge the disconnect: “She has a point — just for the fun of it — because the camera dignifies her.”) This passage gets in the way of an otherwise joyful meeting of the minds, but the structure of “Hopper/Welles” is loose enough that it strips them of their iconography. These are two complicated figures both frustrated by the world and keen on working through it. In Hopper, Welles discovers the potential for a kindred spirit. In the narrative of decline that surrounds Welles’ final chapter, it’s a welcome antidote to see him grow so animated around rising talent.

Forced to pretend he’s engaging with a fictional creation, Hopper never turns the tables on Welles, or asks him about any of the fascinating passages of his own beleaguered career, from the studio clashes of “The Magnificent Ambersons” to the high-stakes experiments of “The Trial” and beyond. While there’s much to appreciate about watching Hopper talk through his curious ambition, “Hopper/Welles” leaves the impression that a reverse shot of the interrogator would tell a very different story, and it deserves to be told one day as well.

Grade: B

“Hopper/Welles” premiered out of competition at the 2020 Venice Film Festival. It is currently seeking U.S. distribution. Sign Up: Stay on top of the latest breaking film and TV news! Sign up for our Email Newsletters here.