SOMETIMES a moment that doesn't seem important at the time later turns out to have been a turning point. Like when Frank Marshall was working in Rome in 1973 as location manager on Peter Bogdanovich's Henry James adaptation Daisy Miller and he got a call from Universal publicist Gerry Lewis.

"I've got a young filmmaker with me, " Jones said. "He's kind of homesick. He'd like to talk to some Americans. He's on his first publicity tour for a little TV movie he's made called Duel. Can we come by?"

Marshall set up a lunch in the Sofapolitino studio canteen. "I got to the table late, because something was happening on the set, " he says. "Peter and Cybill Shepherd were there and this kid Steven Spielberg who was my age, maybe 27, and Verna Fields, who went on to edit Paper Moon and Jaws was sitting there too.

"I got introduced to Steven, checked some things with Peter, took a bite and went back to work. Verna later told me that Steven turned to her and said, ?that's the kind of guy I need, a guy who's much more interested in what's going on on the set than lunch'."

"Five years later, on the beach in Hawaii, George Lucas and Steven were talking about Raiders of the Lost Ark and George said, ?Well who do you want to produce this?' ?Let's see if we can get that guy Frank Marshall, ' Steven said. So, later I got this call, ?Is this the Frank Marshall who works with Peter Bogdanovich? Well this is Mr Lucas's office.

Could you come in and have a meeting?'" Marshall, who will be 60 in September, laughs. "So the moral is, always do your best because you never know who's going to be watching. Sure enough I was available when I got that call and that's when I started working with Steven."

Marshall and Spielberg got on so well producing Raiders of the Lost Ark that they formed their own company, Amblin, with Kathleen Kennedy - who became Marshall's wife - and went on to make Poltergeist, ET, The Color Purple, Empire of the Sun, and the Back to the Future trilogy, as well as two more Indiana Jonesmovies. "It was really just being in the right place at the right time, " says Marshall.

He left Amblin in 1991 with Kennedy to form their own production company when Spielberg got the idea of setting up DreamWorks. "We wanted to continue making movies ourselves and Steven wanted to be a studio, " he says. "We both appreciated that.

We're still good friends making movies together. But I just couldn't be in an office at a desk. I had to be out there. When I was growing up in California I sailed a lot. I loved the outdoors" He first got into movies as a location manager for Peter Bogdanovich on The Last Picture Show. "That's the great thing about making movies for me. You get to live in all these worlds you are creating. I didn't know anything about horseracing, for instance, when I was making Seabiscuit with Gary Ross. And now I get invited to the Kentucky Derby every year. In The Last Picture Show I got to hang out with the kids in the high school in that little town of Archer City where life revolved around the local cinema and everything died when it closed. I understood what that way of life was."

So much so that Bogdanovich got him to play one of the characters, the high-school quarter back. "There was a scene - and this was long before Brokeback Mountain - where the Tim Bottoms coach, who had a thing for his boys, was with me in the locker room, but luckily there wasn't time to shoot it."

Marshall has been second unit director for Bogdanovich, Spielberg, Robert Zemeckis and Gary Ross. He shot Shanghai scenes for Spielberg's Empire of the Sun. "It turns out that they're the last 35 mm footage of the Shanghai skyline as it was, " he says. "Now it looks like Berlin, it's so modern."

The job of the second unit director is to imitate the first unit director. "So I'd get to find out why and what they were doing and try and create something like they would.

There are a lot of my shots in all their movies. I think it's led to me developing my own style and learning how to tell a story."

So much so that when he came across Eight Below, a story of a team of husky dogs marooned in the Antarctic and the man who braved the elements to go back for them, he decided to direct it himself, just as he did with Alive! - the plane-crash survival story set high in the Andes. "I love stories that are a challenge. People ask was it hard taking a big crew into sub-zero temperatures. To be honest, it was great. It became almost spiritual, the landscape was so beautiful."

Although Eight Below was shot in northern Canada and Greenland rather than Antarctica - it would have been impossible to operate with a large crew - nothing was faked. "It was just the elements and us.

We shot to suit whatever the weather was. If there was a blizzard we shot the blizzard scenes. We never stopped. I love the challenge of being inventive. I don't know what it is but you can't fake that reality. If you look at something that has a CG background, it looks too perfect. Because you can't create imperfections that are there in real life. CG is a wonderful tool, but it kind of makes some of us lazy. In the old days you had to compose a shot to hide - say - that one new building intrude in a period scene, and it made you creative. But today you just go, oh well, we'll take it out. So it's not as interesting a frame."

Part of the appeal of the Indiana Jones movies that he produced for Steven Spielberg is that nothing was fake. "Everything you saw was being done and it was believable. That's a real ball rolling behind Harrison Ford and he really is in some danger running in front of it. When he's being dragged under the truck, that's a guy - Gerry Leonard - and it's a real truck on a dirt road in Tunisia. We did it the old-fashioned way.

Let's say we'd put him on a green screen.

Something would be missing. Because whoever is doing the CG doesn't know exactly how the dust would be. You may not know why, but it looks fake."

Marshall has reunited with Spielberg and Ford for a fourth Indiana Jones adventure.

"We're going to have the same elements.

We're not going to come out of the genre we created. We're going to play it as Harrison is.

He's not going to do things that are preposterous. It'll all be within the limits of the age he's playing. He's another guy trying to deal with real things rather than like his counterpart James Bond, who's fun because no one could ever do the things he does."

Marshall went for the same realism when he produced The Bourne Identity with director Doug Limon and The Bourne Supremacy with Paul Greengrass. "Paul is coming back for the third movie The Bourne Ultimatum.

He's a real film-maker. He gets the genre. He understands the reality of what we're trying, but it's also got its own elements that he has helped create. Although the character and set-up is what we took from the Robert Ludlum thrillers, we've gone into our own realm because Ludlum's books were all about the Cold War. I think people are attracted to the Bourne character because he gets out of situations by using his head rather than a watch that kills people. They become concerned about his dilemma and how he deals with it."

Marshall is also working with Spielberg on a fourth Jurassic Park. "Now where digital effects are really justified. There's no other way you could create believable dinosaurs.

We have a good script and should have it up and running next year, for release in 2008."

Marshall's father was a musician. "I remember growing up and always having these great jazz musicians around . It was a really creative free-form atmosphere. They loved what they did. It wasn't about what are you going to pay me to come over. I remember going to clubs where they just loved to play together. I always thought if I can find something that can be that way that's what I'll do. I never thought it would be movies."

Perhaps that's where Marshall's penchant for improvisation comes and not relying on computers. "Movies are not just what's in the script. They're about saying, ?Oh let's try this'. I didn't get the lead guitar gene from my dad, I got the rhythm guitar gene. Now I'm hopefully doing that making movies. "