Robert Drew, far right, holding microphone during the making of his first major documentary, “Primary,” in 1960. John F. Kennedy is seated to the left, and his chief challenger, Hubert Humphrey, is standing with arms folded. (Courtesy of Drew Associates)

Robert Drew, an innovative filmmaker whose intimate documentaries captured compelling moments during the campaign and presidency of John F. Kennedy and whose unadorned style influenced generations of documentarians, died July 30 at his home in Sharon, Conn. He was 90.

The cause was sepsis, his daughter, Lisa Drew, said.

In the 1950s, Mr. Drew, a onetime fighter pilot and Life magazine correspondent, organized a team at Time-Life that sought to create a new way to make television documentaries. Experimenting with cameras and sound equipment, they developed portable handheld devices that allowed the filmmakers unprecedented access to their subjects. The results were revolutionary.

Mr. Drew’s first major documentary, “Primary,” chronicled the final days of the 1960 Democratic presidential primary in Wisconsin, focusing on Kennedy and his chief opponent, Sen. Hubert H. Humphrey of Minnesota.

The grainy black-and-white documentary captured Kennedy in the full glory of his youthful charisma, but it also showcased an utterly original form of non­fiction filmmaking. There were no interviews, no special lighting, no music and almost no narration.

The story was told through images and the candid comments of Kennedy, Humphrey and key figures in their campaigns. The artistry came in the way the film was edited, with the drama growing organically from the footage recorded by Mr. Drew’s unobtrusive team.

One of the most dramatic scenes in “Primary” shows Kennedy walking through a backstage crowd, shaking hands and chatting as he moves toward the podium. The camera, directly behind the candidate, is so close that at times the viewer can see individual strands of his hair.

Although “Primary” was shown only on a few television stations when it was completed in 1960, it became a sensation among filmmakers, who soon applied its daringly simplified approach to other documentaries and features. “Primary” is considered one of the cornerstones of what Mr. Drew called “direct filmmaking” and what film historians call cinema vérité, or “truth cinema.”

“ ‘Primary’ had as immense and measurable an impact on nonfiction filmmaking as ‘The Birth of a Nation’ had on fiction filmmaking,” film critic Matt Zoller Seitz wrote in 2003. “Drew is the D.W. Griffith of documentaries — the guy who figured out how to show a story rather than tell it.”

Mr. Drew followed the same technique in making nearly 100 documentary films. His 1963 film “Crisis” portrayed the standoff between the Kennedy White House and Alabama Gov. George Wallace (D) over integration at the University of Alabama. It marked the first time that outside cameras were allowed in the Oval Office, observing a president’s decision-making at a tense moment.

Such filmmaking innovations were not universally appreciated at the time. A New York Times reviewer was aghast that the White House opened its doors to Mr. Drew and called “Crisis” a “melodramatic peep show.”

As early as 1950, when he was a young correspondent for Life, Mr. Drew recognized the untapped dramatic possibilities in the new medium of television. Early documentaries were merely “illustrated lectures,” he said, with one thing in common: They were boring.

While spending a year at Harvard University on a Nieman fellowship in 1955, Mr. Drew came up with ideas to make the photo essays of Life come alive. With the backing of Time-Life, he hired a team of engineers and filmmakers to devise a 16mm camera with quieter gears and a zoom lens. Through a synchronized recording system, pictures and sound could be recorded simultaneously.

“The innovations that Drew helped develop brought filmmaking out into the streets and into our lives,” Thom Powers, the documentary programmer for the Toronto International Film Festival, said Thursday in an interview.

Mr. Drew also decided to abandon what he called “word logic” in favor of “picture logic,” in which the narrative drama emerges through images and unscripted dialogue.

“It would be theater without actors,” he said in 1962, “it would be plays without playwrights, it would be reporting without summary and opinion. It would be the ability to look into people’s lives at crucial times from which you could deduce certain things and see a kind of truth that can only be gotten by personal experience.”

Robert Lincoln Drew was born Feb. 15, 1924, in Toledo and grew up mostly in Fort Thomas, Ky. Among other things, his father ran a seaplane business on the Ohio River.

Mr. Drew dropped out of high school to join the Army Air Forces in World War II. He flew 31 missions as a teenage fighter pilot before he was shot down over Italy in January 1944. He spent more than three months eluding capture behind enemy lines before being reunited with U.S. forces.

In Italy, Mr. Drew became friendly with journalist Ernie Pyle, whose personal stories about the troops were well known throughout the country.

After the war, when Mr. Drew was training as a jet fighter pilot, he wrote an article about the experience that was published in Life. The magazine hired him as a correspondent in 1946, and he later became a picture editor, working with such renowned photographers as Alfred Eisenstaedt.

As a journalist, Mr. Drew always remembered the warm, intimate style of reporting practiced by Pyle, who had been killed in combat in the Pacific in 1945.

In one of his final documentaries, “From Two Men and a War” (2004), Mr. Drew described his wartime experiences and his friendship with Pyle.

Mr. Drew’s first marriage, to photographer Ruth Faris Drew, ended in divorce. His second wife and filmmaking partner, Anne Gilbert Drew, died in 2012 after 42 years of marriage.

Survivors include three children from his first marriage, Thatcher Drew of Bronxville, N.Y., Lisa Drew of Fairbanks, Alaska, and Derek Drew of Washington; a brother; a sister; and three grandchildren.

Mr. Drew’s proteges have included such prominent documentary filmmakers as Richard Leacock, D.A. Pennebaker and Albert Maysles. (Maysles, whose films include “Gimme Shelter” and “Grey Gardens,” received the National Medal of Arts this week from President Obama.)

Mr. Drew had many personal interests, including flying gliders, but continued to work on films until shortly before his death. One of his last efforts was a documentary about his wife, Anne, who edited the dance sequences in “Man Who Dances” (1968), an Emmy Award-winning film about ballet star Edward Villella.

Mr. Drew’s films received many other honors, including top awards at the Cannes and Venice film festivals. “Primary” and “Crisis” are included in the National Film Registry of the Library of Congress.

As technology changed, Mr. Drew changed with it. His shot films on videotape and later in digital formats.

He was a member of the Academy of Motion Picture Arts and Sciences, but he wanted nothing to do with Hollywood. He just wanted to peer into people’s lives and tell their stories with as little fuss as possible.

“The idea,” he said, “is to hang back and not be too obvious.”