LEGEND has it that a dull journalist once asked Bob Dylan what his songs were about. As ever, the great man had a quip to hand. "Oh, some of them are about four minutes, some are about five minutes, and some, believe it or not, are 11 or 12," he said.

Todd Haynes's magnificent new film I'm Not There - which, though it may not quite be about Bob, is certainly near him - doesn't replay that incident, but it does feature a great many bemused hacks trying to get various neo-Dylans, proto-Dylans, pseudo-Dylans and anti-Dylans to unlock the secrets of those deliciously puzzling lyrics.

I, therefore, feel slightly self-conscious shuffling towards Haynes with my microphone and my notebook. I feel as if I am turning into one of those flabby-minded pedants in horn-rims.

"Oh yeah. 'What does it all mean? Why are you being so blurry?'" he laughs.

Haynes, one of the most amusing and personable of film directors, may well make a joke of the question, but he must have had to formulate a lucid answer several times over the past five years. When we last met, in the run-up to the release of his masterpiece Far From Heaven, he had just begun to mull over the notion of a film investigating the many faces of Bob Dylan.

That was 2002. In the interim, a great many financiers will have listened patiently to his pitch - six people, including a woman and an African-American child, play six different versions of Bob Dylan - and then calmly asked him what on earth he was talking about.

"I really wasn't asked that question as much as you might think," he says. "They were very polite as they said 'no'. And they did try to make sense of it. I just tried to communicate that the only way to depict somebody this complex and who entered all these creative spaces was to reflect that complexity in the story. I wasn't imposing complexity on a simple, linear life. He is knowable in each place, but when we try and impose a linearity and continuity on him, then he refuses to be legible."

Todd Haynes - who, you won't be surprised to hear, originally studied semiotics at Brown University - has delivered a film every bit as elliptical, poetic, funny and playful as one of Dylan's 11-minute epics. Investigating six vaguely intertwined lives while making allusions to the films of Federico Fellini and Jean-Luc Godard, I'm Not There could not look less like a conventional rock biopic. Cate Blanchett appears as a version of the black-leather heron that shocked the folkies by picking up an electric guitar. Richard Gere plays an aging Billy the Kid. Christian Bale unites the political strummer and the born-again preacher.

Where is the real Bob Dylan? The title of the film (an allusion to a legendary bootleg song by Dylan) suggests we should look elsewhere for enlightenment.

"Absolutely. The self-displacement built into that title was the reason why we chose it," Haynes says. "He is like a flame. Every time you reach out for him, he's not there. That explains the unending desire for him. When a star is there, you cease to desire them. But Dylan remains unique in the way he attracts this cultural swarm around him."

I'm Not There, a purposely opaque exercise in evasion, has, despite glowing reviews, proved to be of minority interest on its release in the United States. The mainstream media has, however, paid some attention to Cate Blanchett's performance. Currently an unbackable favourite for the best supporting actress Oscar, the Australian skilfully treads the line between impersonation and caricature.

"The Dylan of 1966 has become so famous, so well-known that the strangeness of it has been lost," Haynes explains. "The sheer risk, the blood and guts have been forgotten since that Dylan has been canonised. You look at him then and he had become this creature - the hair had gotten weirder, his hands were spinning up from the keyboard."

So casting Cate was more to do with capturing that strangeness than with acknowledging the singer's femininity?

"It's not really a feminine side in those terms of being a sensitive man," he says. The male and female designators had just gotten messed up. If anything, he looked more like what Patti Smith would look like 10 years later than what Bowie would look like. It was a lesbian androgyny."

As you may have gathered, Todd Haynes, now a lively 47, combines a playful humour with a formidable intellect. That combination was conspicuously on display in his notorious 1987 debut Superstar. Using Barbie dolls to tell the story of Karen Carpenter's death from anorexia, the picture (often misunderstood as a sick joke) managed to be surprisingly moving as it allowed its plastic actors to deride unrealistic models of femininity.

One of the most significant figures in the new "Queer Cinema" then emerging, Haynes went on to direct such modern classics as Poison and Safe, before eventually rubbing audiences and critics up the wrong way with Velvet Goldmine. That odd picture, a thinly disguised examination of Iggy Pop and David Bowie, sucked the juice out of him.

"I was really happy with the film," he says. "It was making it that finished me. I remember suddenly realising how little energy I had been putting into my life. I looked around and saw all my peers settling down and getting comfortable places to live. Also, I had a boyfriend who was HIV-positive. So, there was always something to distract from focusing on creature comforts. Life got a lot better when I got out of New York City and moved to Portland."

Contentedly tucked away in Oregon, Haynes set to work on writing Far From Heaven. Though hardly a box-office smash, the beautiful, sinister picture - a tribute to 1950s melodrama starring Julianne Moore - played in multiplexes and was nominated for four Oscars. I imagine Haynes was suddenly offered a great many silly commercial projects.

"There were a few," he says. "I found myself being sent all these films about women in traumatic situations, but none of them appealed to me. Besides which, I already had the rights to do the Dylan film and that's what I wanted to do. Mind you, that ended up being the hardest thing I have ever done. It nearly killed Christine Vachon and John Sloss, two veteran independent producers."

The producers did, at least, have the blessing of Bob Dylan. Presented with a one-sheet summary of the concept and a batch of Haynes's DVDs, the old eccentric clearly realised that, even if it failed, I'm Not There would stay true to his own artistic sensibility.

What word has come from Castle Dylan in the months since release? "There has been no word. He recently got a DVD and has it on tour with him. We have nothing directly from Dylan."

So Haynes has yet to meet the man? "That's right. If I wanted to, I could have set it up. But when I imagined sitting down and talking to him, I realised it would be more about satisfying me than developing the film.

What's wrong with that? "Well, we had too much work to do and I didn't want to feel nervous about that meeting. Maybe we'll meet sometime soon after he's seen it and have a beer and a laugh about it."

I'm Not There is about 135 minutes long. It is released today