Los Angeles filmmakers Dylan Robertson and Bill Ferehawk are framers, much in the way a carpenter frames a door. When Ferehawk, a former architect, sees a Japanese Buddhist temple, he sees a frame. What better way to tell the visual, moving-picture story of the course Japanese Buddhism has taken through Island history?

The pair is here this week on their second trip to the Islands to shoot footage and conduct interviews at myriad temples — from the Pearl City Hongwanji to Honpa Hongwanji headquarters to the Nichiren Mission — for an independent documentary, tentatively titled "Lost in Hawai'i: A Buddhist Adventure," which they hope to release on public TV, among other venues.

Talk about backstory. In its heyday of the 1930s, Buddhism was the dominant religion here, according to Louise Hunter's 1971 book "Buddhism in Hawaii" — a fascinating factoid for a territory with such a rich missionary past.

In 1924, nearly 155 temples existed, according to one expert. Now, there are about 75.

The filmmakers realize that the steady decline of the religion's physical structures adds urgency to the project: How can they preserve and capture something that's rapidly changing?

"The question we're trying to answer is, how do you actually preserve history?" asked Ferehawk. "When it is preserved, what is actually being saved?"

Added Robertson: "The shocking question becomes, what is being saved? Religion? Culture? Can you contain culture and religion in a building not used for its original purpose? It's fascinating how people wrestle with these questions."

Other themes add to the structure.

They ask: How is history seen and remembered vs. how it is actually lived?

For example, today's bon dances on O'ahu are nothing like their contemporary counterpart in Japan, where the departed are commemorated just once a year.

Here, the cultural celebration runs over an entire summer, and dances are often packed with traditional music and style of dress; they can be viewed as an extended effort to preserve moments, so that later Japanese generations can remember the culture of their grandparents' early days.

While here, the filmmakers plan to take in a bon dance or two.

Robertson and Ferehawk's labor of love is shared by local architect Lorraine Minatoishi-Palumbo, who wrote her Ph.D. dissertation on Japanese temples here. She's been labeled "principal scholar" on the project.

"That's a nice title," Minatoishi-Palumbo said with a laugh when she heard it.

Perhaps it makes up for the fact that she's volunteering her time, since, as she joked, "I'm lucky if I get a hamburger at the end of the day."

The question of preservation is truly a here-and-now one, Minatoishi-Palumbo knows. In Koloa on Kaua'i, for example, a century-old Jodo Mission was on the verge of being torn down. She put out the word that it was an endangered structure. That led to a cascade effect: The congregation galvanized to keep it preserved, and Japanese carpenters stepped in to offer their services.

The idea for Robertson and Ferehawk's documentary came from a chance meeting with Minatoishi-Palumbo. The trio met while working on a film about Honolulu's famed architect Vladimir Ossipoff. The filmmakers were seeking background on Japanese carpenters from Minatoishi-Palumbo, who had worked with Ossipoff.

"We just hit it off," Minatoishi-Palumbo recalled. "I liked them, they liked me."

So Minatoishi-Palumbo pitched the idea of a documentary on Japanese temples and even helped them apply for grants, including a $20,000 one from the Cook Family Foundation. It's a subject near and dear to the heart of this third-generation Japanese-American, who grew up with a grandmother who never spoke English.

"For me and most (third- and fourth-generation) Japanese Buddhists, it's such an unexplored subject," Minatoishi-Palumbo said. "... I never knew much about the Buddhist religion. It wasn't foreign to me, but wasn't part of my daily life."

The filmmakers will bring an outside eye, but also a deep respect for the topic, which holds the intriguing distinction of being the only Eastern religion to ever have a place of dominance on what is now American soil: "It really started out as means to raise awareness about what the role Japanese Buddhism has played in Hawai'i," said Ferehawk.

And while Minatoishi-Palumbo wants to ensure it's done right, she's not running the show.

"I leave it up to them to create the story," she said. "I'm just there for the ride."