HOLLYWOOD — “Tell Them Who You Are” helmer Mark Wexler talked about his very personal docu at the Variety screening series.The majority of the Q&A session dealt with the film’s main subject — renowned cinematographer Haskell Wexler, the director’s father. “The film started out about fathers and sons,” helmer said at the Nov. 18 sesh. “But as I started filming my dad, I thought that he is a pretty good subject, so I don’t need any other fathers and sons.’ Wexler interviewed Jane Fonda, Michael Douglas and Milos Forman, but did not succeed in pinning down fellow documentarian Michael Moore or the ever elusive Warren Beatty. The latter said yes, but Wexler never got him after a year and a half of trying. “His assistant and I have become good friends,” Wexler joked.