Les Blank’s long-unseen documentary about rock and roots legend Leon Russell shot in 1972-74 — so long ago that Willie Nelson appears beardless and Blank has died — is here at last. And what a trippy delight it is.

The film focuses on the Oklahoma world of Russell and his circle, as they record music, perform at concerts and shoot the breeze. Interspersed are scenes that at first seem irrelevant, like a beautiful old Tulsa building being torn down. But in fact, this is Blank’s way of capturing a world that the grainy, colorful film constantly hints won’t last.

From the elderly woman who slyly says she finds her husband more attractive with hippie-ish long hair, to Russell’s soaring duet with Charlie McCoy on “Goodnight, Irene,” this is as accessible and as lovable as avant-garde filmmaking ever gets.