Once on set in his hometown of New York, Rubin tried to mimic his nonfiction techniques. "I really would say I didn't direct the movie. I allowed the actors to be themselves," he said.

He shot in long takes, shot the story in chronological order, didn't follow the script too slavishly, and tried to place his cameras so the actors wouldn't play to a specific place.

"I knew I wanted a lot of the actors to improvise the dialogue in a way that felt natural — that they put things in their own language," Rubin said. "I hid my cameras so far away from them that half the time the actors didn't realize I'd already got the reverse shot."

In a way, it's the same in a documentary interview: You want the subjects to relax and open up. "To me, it's all about forgetting about the camera," Rubin said.

"If the camera gets bumped, the camera gets bumped. If a line of dialogue gets stepped on by another actor, the line gets stepped on. I am just bringing the only way I know how to do things to fiction."

The documentary-to-drama path has been successfully traversed by several directors, including Paul Greengrass, José Padilha, Michael Apted, Kevin Macdonald and Werner Herzog, among others.

Rubin has made dozens of commercials since filming "Disconnect," and isn't sure he's ready to give up advertising. Shooting "Disconnect" "makes me really enjoy making commercials. They are such a delight — these little adventures you get to go on," Rubin said a few hours before heading off to Alaska to work on a new spot. "And the more I make commercials, the more the clients are starting to listen to me."

As naive as Rubin might have been when he started making "Disconnect," he isn't certain he's all that wiser for the experience.

"It was a grand experiment. I really have no idea how it turned out," he said of the film, which has attracted mixed to positive reviews. "I don't pretend to know what we made."

john.horn@latimes.com