Robert Benton has seen more than one cinematic revolution in his time. He and his late screenwriting partner, David Newman, were major players in two films that forever changed movies: 1967’s “Bonnie and Clyde,” which brought European New Wave aesthetics into mainstream American cinema and permanently altered the portrayal of violence in American pop-culture, and 1978’s “Superman,” which created the big-budget superhero flick and convinced the world Christopher Reeve could fly. But as the writer and director of a little movie without violence, groundbreaking special effects, or even a whole lot of controversy, Robert Benton actually helped change real life with 1979’s “Kramer vs. Kramer,” about a careerist father (Dustin Hoffman) raising his son alone after being left suddenly by his wife.

Drawn from a novel by Avery Corman, the film was an immediate critical and box-office success, ultimately making over $100 million. It proved to be a star-making role for the twenty-something Meryl Streep, who won a Best Supporting Actress Oscar as Hoffman’s ex-wife, who endures a change of heart and sparks a painful custody battle. Moreover, it racked up a historic Oscar nomination for seven-year-old Justin Henry in the crucial role of Billy Kramer, and garnered both a Best Picture award and a Best Directing Oscar for Benton against an exceptionally strong group of nominated films that included “All That Jazz” and “Apocalypse Now.” Still, lots of movies have received acclaim, Oscars, and a tidy profit. “Kramer vs. Kramer” is a different story.

The truth of the matter is that in 1979, the rise of “women’s lib” notwithstanding, child rearing was still widely regarded as primarily a job for mothers, with fathers routinely playing secondary or tertiary roles — or no roles at all. Within a few years of the release of Robert Benton’s little film, however, any man who tried to fob off too many childcare duties on his significant other or ex was seen as an irresponsible boob. Obviously, no movie can institute that kind of cultural change all on its own, but “Kramer vs. Kramer” was undoubtedly a landmark in that quiet but pervasive part of the ongoing struggle toward gender equality.

And that was my first question when I was part of a short interview round-robin with Mr. Benton and the now entirely grown-up Justin Henry prior to a special screening promoting the Sony Blu-Ray release of “Kramer vs. Kramer.” Mr. Benton, whose reputation for being a charmingly self-effacing interview subject preceded him, was characteristically modest and generous when I asked him to what degree he was conscious of the possible import of his low-key drama.

“Sometimes you do work to explain what you already know, and sometimes you do work to figure out what you don’t know,” Benton began. “Being a father was probably the most extraordinary change in my life. There was a tectonic shift in what I thought life was about, and, suddenly, it was no longer ninety-nine percent about me.” Adding a bit of Bentonian wit, he added, “It was now ninety-eight percent about me….but, somehow, there is someone you love more than you love yourself…and I was wanting to talk about that in this film, and Dustin and Stanley [Jaffe, the producer] felt the same way.”

Benton went on to emphasize the contribution of his collaborators, adding that he felt the film had not one but three or four “authors,” definitely including the film’s director of photography, Néstor Almendros, who died in 1992. “The sensitivity of his work rivals any DP of the 20th century and he was a great teacher to me,” said Benton. He was also quick to praise the contribution of producer Jaffe and his famous cast…including, of course, Justin Henry, who was sitting just to his left and who chimed in with some praise for Benton’s work as a filmmaker on “Kramer.”

“I’m amazed at how well it has held up,” said Henry, who, contrary to ex-child-star stereotypes, appears entirely levelheaded and nearly as low-key as his onetime director. “It’s nice to see people making movies about people, instead of just making movies about situations.” Asked about whether he was aware of the fact that he was a seven year-old costarring in a major Hollywood film with a superstar, Henry was matter of fact in stating that he hadn’t a clue. In fact, Benton chimed in that he didn’t know what he’d be doing or saying on any given day until he showed up on the set. “I wish it could still be that simple,” Henry, who appears frequently in independent films, joked wistfully.

After that, the discussion ran to Dustin Hoffman’s character, who begins the film as something less than an ideal husband or father and makes a remarkable, though subtle, transformation into someone who is far more compassionate and aware of his own failings. “He was forced into something he didn’t want and then he has to learn something he didn’t know how to do,” Benton says, adding that a later moment in the film, when he confesses his shortcomings as a husband to his son, was the only time he’d seen the famed method actor overwhelmed by the emotion of a scene and unwilling to do another take.

After that conversation ran to questions about whether something like “Kramer,” could be made under today’s studio system. Not surprisingly, Benton believes it would have to be made independently. “I don’t think they would make it today because I think there’s been an enormous shift in film. Even in the late seventies, the studios were still owned and run by entrepreneurs….and a business that is run by entrepreneurs makes decisions in a different way than a corporation which is a public company and responsible to the stockholders. I’m not saying one is right and one is wrong, I’m just saying they’re different models.”

Asked about the competition for the Academy Awards in 1980, Benton proves to be a canny Oscar observer. He wasn’t worried about being beaten by “Apocalypse Now” since the prior year’s winner had been “The Deer Hunter” and it seemed unlikely that the Academy would honor two Vietnam War films in a row. Later, when asked if he had favorite films he was rooting for in the Oscar’s that would be taking place later in the week, he proved even cannier about Hollywood politics: “I have my favorites and film’s I’m rooting for, but I’m not going to tell you what they are,” he said with a smile. He did, however, offer unqualified praise for the critical favorite, “Let the Right One In,” a creepily haunting, unsentimental tale of childhood vampire love from Sweden that’s a kind of anti-“Twilight.”

Indeed, for a septuagenarian director primarily associated with intimate tales of daily life, Benton seems to keep up with geek culture and is proud of his own contribution. When I reminded him that not only had helped birth the modern superhero film with “Superman” but that he and David Newman had also co-invented the super-powered musical with their book for Broadway’s “It’s a Bird, It’s a Plane, It’s Superman” (later presented on TV and fondly remembered by yours truly) and mentioned last year’s Internet hit, “Dr. Horrible’s Sing-Along Blog,” Justin Henry gave him a knowing nudge. Discussing the lingering appeal of that first superhero film epic, he is characteristically quick to share credit. “I am astounded at all the people who come up to me and talk about ‘Superman’ and talk about how much they loved it and how important it was to them. I thought it was terrific and [director] Dick Donner did a great job. And he brought [script doctor] Tom Mankiewicz in…and I thought [his] work was really good. And obviously Chris Reeve was extraordinary and Margot Kidder was great.”

Still, the main topic of the night was “Kramer vs. Kramer,” which was screened via Blu-Ray to fairly impressive effect at Beverly Hills’ Fine Arts Theater. When a series of sound problems severely slowed down a post-screening Q&A with Benton and Justin Henry which was intended to be used as an online Blu-Ray DVD extra, Benton used the opportunity to discuss numerous aspects of the making of “Kramer” including how, as with “Bonnie and Clyde,” he had originally intended it to be directed by France’s most popular New Wave director, François Truffaut. He also discussed in detail how an initially uninterested Dustin Hoffman was wooed into becoming involved in the project, and how young Justin Henry was found and became the youngest Oscar nominee in the award’s history.

Benton started with the idea that actors come in “weight classes” and that he knew what he needed was a seven year-old capable of “taking on” Hoffman. “[At the auditions] I told Dustin, ‘throw everything you have at these kids, because if they can’t take it, we’ve got to find out now’….and the one person who gave back as good as he got was Justin. He had this authority,” Benton added, describing it as a God-given gift. “I’m a big believer in God-given gifts.”

As the technical problems lingered, Benton, the avuncular trouper, kept talking — not so much about himself but about his collaborators. He discussed enlisting Hoffman as a sort of co-director in working with Justin Henry to bolster the film’s parental on-screen relationship; how it was Benton’s wife who originally persuaded him to adapt Avery Corman’s novel; the influence of the French New Wave on his style in general and how much he would have liked Truffaut to direct “Kramer”…and so on.

Still, as luck would have it, Benton wound up directing the movie himself and beating both Francis Ford Coppola and Bob Fosse, two of the late twentieth century’s greatest directors at or near the top of their respective games, for the best directing Oscar. Under those circumstances, Robert Benton’s famed modesty isn’t only endearing, it’s somewhat miraculous.