When 2001: A Space Odyssey premiered nearly 50 years ago, few cared for it. The New York Times called it ''somewhere between hypnotic and immensely boring'' and respected critic Pauline Kael declared it a ''monumentally unimaginative movie''. Nearly 250 people walked out of the New York premiere.

But Gary Lockwood, who played Dr Frank Poole, one of five astronauts voyaging to Jupiter in the Stanley Kubrick sci-fi epic, remembers one prominent fan.

''When the picture played in London it went for one year on hard sales,'' Lockwood says. ''And John Lennon bought two seats to every performance and gave them away.''

Lockwood, who is in Sydney for a screening and a Q&A session, terms 2001 a ''life-changer'' in terms of technology and the possibilities of film. During filming he knew its effect would be both profound and magisterial.

''Our society was ripe for it,'' he says. ''It wasn't so much my brilliance, it was more that the young people in America were knowledgable about the space program and very knowledgable about sci-fi.

''And when you've got the best moviemaker of all time, Stanley Kubrick, with one of the best sci-fi writers of all time, Arthur C. Clarke, combining, well, I kinda knew.''

A ground-breaking, prophetic film exploring artificial intelligence, evolution and alien life, 2001 was partially inspired by Clarke's 1948 story The Sentinel.

He and Kubrick took 10 years to develop, co-write and film what is now considered the greatest sci-fi film of all time.

''We didn't shoot at a normal pace,'' Lockwood says. ''One sequence took almost a week to get and there were only a few shots in it.

''When the centrifuge - the big wheel in which we lived - turned, it had 20-something movie projections attached to the outside, and 16-millimetre [film] making the TV screens of the various stations. I mean it is the most elaborate movie ever made.

''There are no computer graphics, it's all models of different sizes. It's a handmade movie.''

Famous for being a perfectionist who required numerous retakes, Kubrick nearly doubled the film's $US6 million budget and delivered it 16 months late.

''Within a very short period of time I realised that Kubrick was the brightest director I'd ever worked for,'' Lockwood says. ''He wasn't a taskmaster like everyone may, or may not, say. He was very intelligent, very much a gentleman.''

Lockwood's career has also featured roles alongside Elvis Presley, Natalie Wood, Warren Beatty, Stefanie Powers (whom he married), James Stewart and Henry Fonda. Steve McQueen was a close friend.

''I do spend a lot of time being asked about the people I have worked with,'' he says, chuckling.

In 1966 he played Lieutenant-Commander Gary Mitchell in a sci-fi pilot that garnered a wholly different league of fame. The pilot episode, Where No Man Has Gone Before, was the reason Star Trek appeared on TV.

But 2001 is Lockwood's most profound project.

''I remember Warren Beatty came up to me when we were all smoking during intermission at the movie house,'' he says. ''He stuck his head in the group, looked at me and said, 'You're lucky'.

''And I knew I was because in an actor's career, you don't often get a chance to do something that will last forever like that.''

2001: A Space Odyssey - A Live Event is at the Cremorne Orpheum on Friday night.