It’s no wonder that Schrader, whose résumé to date includes a movie about a father searching for his lost daughter in the bowels of L.A.’s porno underworld, another about a city-dwelling porn consumer who exacts righteous vengeance on the pimp of the girl he loves, and yet another about a brother and sister pair who turn into goddamned leopards every time they fuck, would be drawn to this curiously American story of celebrity gone wrong.

The star of the show is Greg Kinnear, himself a former radio-show host, who plays Crane’s earlier years as an unassuming DJ and amateur drummer with an aw-shucks grin and effortless charisma. Kinnear’s weakness as an actor has always been a certain stiffness of demeanor, but here it works in his favor, playing in tandem with the relatively uptight environs of Schrader’s mid-1960s middle America. The joke is that Crane, an all-American family man, is underneath the surface a truly randy bastard who’s ready to pop out of his trousers at the sight of the first dame to give him a lingering glance.

There are several pernicious influences on Crane’s moral life. The most rigorous is a skeevy AV dealer named John Carpenter (Willem Dafoe), who takes him out on the town to dive bars and burlesque shows. Another is his newfound celebrity, which gives him extra mileage with the ladies. And the third is video technology itself, the erotic implications of which aren’t lost on Carpenter, a lecherous bastard who sees in his celebrity clients the opportunity to hook up with woman who wouldn’t normally give him the time of day.

Solid performances go a long way here, with Kinnear’s descent from amiably goofy TV personality to aging lounge lizard particularly startling. Defoe is creepily seductive and repulsive in various measures, depending on which reel he’s in. As the film progresses, his haircuts get worse and, though it seems impossible, his skin gets even more leathery. The relationship between the two of them is subliminally sexual and occasionally contentious, culminating in a scene about halfway through where Kinnear suddenly demands, "What the hell is that on my ass?"

Despite its pure function as a representation of pride going before a fall, the first half of Auto Focus is marvelous in a way — smart, sexy, funny. The staged burlesque shows, behind some of which Crane can be seen innocently drumming, are enticing and titillating in a way that may be nostalgic; ditto on the Bunny Yeager pinups displayed underneath the main titles. I’d assume Schrader had a lot of affection for these images if his film didn’t seem simultaneously so mistrustful of them.

As he descends into a hell of his making, Crane’s exploits proceed with a singlemindedness and self-absorption that are made explicit in the fim’s too-clever title. Schrader mechanically underscores the descent with every variety of movie trick at his disposal, including special photo processes, the ever-popular shaky-cam, and creepy music droning on the soundtrack. The tricks occasionally play dividends, as when Schrader zeroes in on Carpenter’s desperation during one contentious phone call by zooming in on Dafoe with a particularly long lens, compressing space and sending different parts of his face in and out of focus. But the weird, grainy colors and spook-show audio mostly manage to make this crap only superficially more interesting. The resulting saga is an entertaining but shallow depiction of a peculiarly American kind of tragedy.

Anyway, the coup de grace — the punchline that makes Schrader’s lecture almost worthwhile — isn’t to be found in the movie. Instead, lucky for us, it’s on the Web. Bob Crane’s son Scottie has gone into the family business, offering access to Dad’s homegrown porno stash to anyone willing to shell out $3.95 for three days of access to www.bobcrane.com. If video technology enabled the creation of a sort of electronic abyss into which men can stare as they stroke themselves off, the Internet lets you parlay someone else’s private hell into a quick buck. That’s some kind of progress.