All in all, this isn't a bad year for artist documentaries. The Drew Struzan film is out there somewhere, and now here's the trailer for For No Good Reason, chronicling the last decade-and-a-half in the life of gonzo cartoonist Ralph Steadman.

Steadman's immediately recognisable, chaotic ink work has graced the pages of Rolling Stone, Private Eye, Punch, The New York Times, and countless books and ads. He used to illustrate Will Self's column in The Independent, but perhaps his most famous long-running collaborations are with William Burroughs and, especially, Hunter S Thompson. Johnny Depp's performance in Terry Gilliam's Fear And Loathing In Las Vegas is arguably as much based on Steadman's signature caricature of Thompson as it is on Thompson himself.

Speaking of Depp, he's on-hand here to guide the audience through the World of Steadman. The doc examines Steadman's influences, and the impact he himself has made on the cultural landscape, and of course, showcases his prolific artistic output.

The film has been fifteen years in the making, and is shot on various formats, from 35mm to HD, as the technologies developed around the filmmakers. A camera was stationed above Steadman's work table for most of the colossal shooting period, capturing everything he created, from blank canvas to finished work. "It's a very odd idea," says the self-effacing artist. "As I go through things, I suddenly realise I've done too much!"

Along with Depp, there are contributions from Richard E. Grant, and from Terry Gilliam, who claims, somewhat alarmingly, that Steadman "doesn't separate his life from his work; it's all one big thing." There's a glimpse of Burroughs in the trailer, and a typically crazed appearance from the late, great Thompson.

There's a cool soundtrack too, with new music from Slash, The All American Rejects, Jason Mraz, Ed Harcourt, James Blake, Crystal Castles and various others. For No Good Reason is directed by Charlie Paul and produced by Lucy Paul, and gets its world premiere at the BFI London Film Festival on October 12.