Dito Montiel says Robin Williams sometimes goofed around on set while filming "Boulevard," but the director says more often, the late actor spent the time between takes contemplating what his character would do next.

"Sometimes he'd do a show for sure. That's kind of him. Then sometimes he's sitting there really thinking about the character," says Montiel. "He really cared about the characters a lot."

"Boulevard," which opened in New York on Friday, is Williams' last dramatic role to be released following his death last summer.

In the film, which expands to other theaters on July 17, Williams plays a closeted gay man who comes out in his 60's and then leaves his lifelong love, his wife of 40 years, played by Kathy Baker.

Montiel says he was thrilled when he got a call saying Williams wanted to talk to him, but he never dreamed it would be about this indie film.

"I was like, 'Whoa, that's crazy,'" the director says, thinking maybe it was about a new "Mrs. Doubtfire," which was rumored to be up for a sequel.

Montiel says he "loved" working with Williams on "Boulevard" and even though he was an admirer, he was a bit surprised at how well Williams immersed himself in the role.

"He won an Academy Award for being a dramatic actor, so I was not that surprised he could tap into it," the director says. "I was surprised at how well he could, honestly, because you have this pre-conceived notion about a lot of famous people."

Montiel, who admits he still keeps some of the phone messages Williams left him, says it was "incredible" getting to know the actor while they worked on the film and says it was even better to hear Williams say he was pleased with his performance.

"All I kept thinking was, 'Man, I hope he really likes it' and he really liked it," Montiel says. "I miss him. It was really nice to make a movie with him."