Over the last decade,Dawn Porterhas emerged as one of the most important documentarians today, with a succession of major films to her credit, including 2020’s “约翰·刘易斯:好麻烦” and the 2018 four-part Netflix series, “Bobby Kennedy for President.”

For her achievements, Porter will receive the Honors Award at the seventh annualDocLands film festivalon Thursday, May 11, where after the ceremony, there will be the California premiere of Porter’s latest film, “The Lady Bird Diaries.” Her new work about yet another enlightened political figure is based on an audio diary that Claudia “Lady Bird” Johnson kept during the years that her husband, Lyndon B. Johnson, was president.

“Dawn epitomizes everything that the DocLands Honors Award means,” said Joni Cooper, DocLands’ director of programming, “not only in the humanity she shows in her filmmaking but in the subjects she chooses for her films as well.”

LikeKen Burns(“The U.S. and the Holocaust”), Porter is steeped in history and takes an even-tempered approach that is not about venting emotion but about inciting emotion and thought in her audience. Also like Burns, her work has a way of leaving viewers better, even while never sugarcoating the realities of a subject.

“I’m optimistic to think what so many people have accomplished in their lives, based on their determination, their creativity, their desire to make things better for everybody,” Porter told The Chronicle just days before the five-day festival, which kicks off Wednesday, May 10. “I think that all the people who are the subject of my films fall into this category.”

Kennedy certainly did. Porter took an unusual approach to telling his story. Instead of ending with his 1968 assassination, the documentary continued for an entire extra episode, exploring the legacy of JFK’s nephew. Porter couldn’t make his story a happy one, and she didn’t try. But she found the lasting good he was able to achieve and inspire, despite not living to become president.

“Bobby Kennedy was born into wealth and privilege, but then he used that privilege for great good,” she said. “We’re already familiar with bad news, and bad news leads in the headlines. It’s easy if you’re a liar or a cheat. It’s a lot harder if you choose to calm the waters and ask, ‘How can I help?’ ”

Porter’s “The Lady Bird Diaries” is based on 123 hours of audio recordings that Lady Bird Johnson made while in the White House — and the film is revelatory. A first lady who many may have thought of as a doormat for her husband emerges as a trusted adviser, critiquing President Johnson’s television performances.

Indeed, going into the project, Porter admits she “knew nothing about Lady Bird. I never thought about her for a moment, and I think a lot now about why that is. I never thought about the fact that Ididn’tthink about her, even though I made all these movies about this period of time.”

As for her strategy of letting Lady Bird narrate the entire film, Porter recalls thinking, “Nobody is going to speak for her; let’s let her finally speak for herself.” That’s why there are no talking heads, Porter simply combines archival footage with the sound recordings of Lady Bird to striking effect.

At one point, Lady Bird holds a luncheon with various prominent women, among them the sultry singer and actress Eartha Kitt. We hear Kitt stand up and ask some pointed questions about Vietnam, clearly expressing her disapproval of President Johnson’s policies, and here the documentary so locks viewers into Lady Bird’s perspective that we see things through her eyes and wish Kitt would stop embarrassing Lady Bird.

“That’s the joy of movies, to have that experience,” Porter said, “so long as you’re clear with people. Here, for me, my transparency as a filmmaker is important. This isher story— what it feels like to be in a gilded cage, while trying to improve the world and benefit your family and support your husband and raise two daughters.”

Porter describes Lady Bird as “deeply thoughtful” even as she was “straddling an era (as) a 1950s wife and mother looking down the barrel of the tumultuous 1960s,” Porter said. “It’s interesting to see the totality of what she’s dealing with, to stop and think about how other people see things.”

Even accounting for the narrow perspective that comes from living inside a gilded cage, Lady Bird comes off quite well. A first lady known for her mission to beautify America’s highways turns out to have been a successful advocate for legislation supporting conservation. She was also something of a seer. Four years before it happened, she, on tape, can be heard predicting that her husband would announce in February or March 1968 that he’d not be running for a second term. That came to pass on March 31, 1968.

In 1964, she had encouraged her husband to run. By 1968, she was relieved to be returning to private life.

“I hope this documentary gives some empathy, not only for Lady Bird Johnson, but for Hillary Clinton, Michelle Obama, even Melania Trump,” Porter said. “They didn’t pick this life.”

Reach Mick LaSalle:mlasalle@sfchronicle.com