Imagine a close-up shot of Joan Rivers, the 76-year-old comedian, without makeup.

That's the first scene of a new film about the iconic comedian, screening in Sundance's U.S. documentary competition. The opening offers an immediate reveal, exhibiting how the trailblazing female comic isn't afraid of being vulnerable in front of the filmmakers who trailed her for 14 months.

"At this age, I am what I am," Rivers said in an interview before her trip to Sundance, and before she saw the film about her. "When I turned 70, I said, 'I don't care.'"

Directors Ricki Stern and Annie Sundberg's 84-minute film offers that blemishes-and-all approach to Rivers' lengthy and varied career. "We deliberately wanted to focus on her performance, her passionate comedic talent," said Stern at Monday's question-and-answer session after the documentary's premiere.

Rivers said she choose not to second-guess the filmmakers. She allowed herself to be the subject of a film, in part because she is a good friend of Stern's mother, and in part because she wanted her struggles and progress documented.

"No one has shown a woman alone, on the road, facing the demons, and age," Rivers said. "I [didn't] want talking heads talking about how great I am ... I hope and know it won't be [full of comments saying] 'Oh, she's so great.' That is so boring."

The documentary reveals how much of Rivers' humor comes from self-doubt and anger. "That's an accurate assessment of every comedian," Rivers said.

The comedian said she was thrilled about attending Sundance, and even bought a new pair of Uggs for the occasion. "I'm beyond excited," she said. "I'm very shallow. I hope [audiences] love it."

But by the end of the conversation, Rivers couldn't help reassessing her opinion about the film's audiences. After all, she is who she is.

"What do they get out of it?" the sharp-tongued, whip-smart comic asked rhetorically. "Who cares?"

dburger@sltrib.com; movies@sltrib.com