When it comes to documenting music, Cameron Crowe is the current king. His Pearl Jam doc -- 20 -- was a feast for the eyes and ears, whether you're a PJ fan or not. So I'm looking forward to Thursday's airing of The Union -- his look at Elton John and Leon Russell -- at 9 p.m. on HBO.

In The Union, Crowe's camera is focused on the creative life of Elton and his collaborative album with Russell, his early-career idol. Begun in November 2009, the film chronicles the entire writing and recording process of the album John recorded with Russell.

Do these two new documentaries from Crowe signal a departure from his feature-film career? Yes, and no, he explains to Rolling Stone.

"I'm going by the Scorsese grid," Crowe told the magazine; Scorsese tackled a feature film (The Departed) at the same time he handled a documentary (Bob Dylan's No Direction Home).

Expect more music docs in the meantime, he hints. "I can't stop!" Crowe said. "I just love music."

Catch a trailer of the movie below.