That tripod figures prominently in Paul Schrader’s well-crafted look into the dark side of Crane’s life as well as his death. “I always wanted to make an impression,” intones a very chipper and very dead Crane (Greg Kinnear), in the well-modulated tones of the radio announcer he once was.

Depicted here as just a regular guy (so normal, in fact, that he wears a cardigan with his pjs) this regular Joe begins the film hard at work, trying to break into television. Very quickly, though, the affable actor becomes a sex-and-video obsessed has-been, deserving of derision and our sympathy. Crane certainly left an impression, but perhaps not quite the one he intended.

Working from Michael Gerbosi’s intelligent screenplay, Schrader keeps Crane a cipher. Rather like a traffic accident unfolding before our very eyes, the actor’s life is slowly transformed. Especially once he achieves celebrity in the mid-’60s, when he realizes that many women are now available to him and he slowly begins devoting more and more time and energy to his sexual encounters. First using a cumbersome still camera, Crane soon gravitated to the new technology of videotape. But what’s missing, however, is any kind of explanation about how Crane got that way.

Crane’s life and death, as depicted in “Auto Focus,” was something of a mystery. An ironic one to boot, as he was both a participant and a voyeur in his own sex life, watching his tapes in the company of his friend and fellow sexual adventurer John Carpenter (not the famous director), played by Willem Dafoe.

We in the audience become voyeurs as well, as the camerawork in the film becomes increasingly (and intentionally) shaky and intimate, and the story digs deeper and deeper into forbidden territory.

Kinnear, whose good looks are of the nonthreatening, unremarkable gene, is well-cast as Crane: He lets us see only what Crane might want us to see and keeps the rest in shadows.

In “Auto Focus,” we see Crane enjoying the perks of celebrity; he loves being recognized, for instance, especially after his “Hogan’s Heroes” fame has peaked. But he’s puzzled when his first wife (Rita Wilson) is shocked by finding a stash of photographs; he seems genuinely surprised that she would be so upset, and we can’t quite tell if he’s really harboring a more telling reaction.

Was Crane a sexual maverick, a man operating under his own code of behavior and reveling in the freedom of the free-love years? Or was his behavior covering something else, something much darker and sadder? Kinnear’s portrayal hints at the latter, but gives us nothing concrete.

Though its focus is specifically Crane and his sexual predilections, “Auto Focus” is also the story of a man’s self-destruction. An immensely sad tale of someone having everything and blowing it.

Bob Crane died in 1978, beaten to death with that tripod while he slept in a cheap motel room. His murder was never solved. Even more tragic and profoundly sadder than his unsolved death is the fact that his son supports himself off his father’s sordid story. For a fee, Crane the Younger allows anyone access to the videos of his father’s sexual activities.

When the lights come up and the credits begin to roll, you’ll find yourself disheartened and depressed. And for good reason. ****