THE story of Seamus McGarvey is not a typical Hollywood tale but it is spectacular none the less. In just six years the native of Armagh in Northern Ireland has emerged from the anonymous realm of documentary camera work to become one of the most noteworthy cinematographers on either side of the Atlantic, a man in the mystical business of lighting up the stars.

Shortly he will begin shooting Kevin Spacey's first directorial movie, a biopic of the seminal 1960s singer, Bobby Darin, in which Spacey will play the lead. But it has been the subtlety of McGarvey's skill on The Hours and before that his wry, unforced finesse on the whacky comedy, High Fidelity, which has illuminated his own list of credits, commanding the attention of the entertainment world's most competitive and fickle trade.

Five years ago, at the age of 30, he became the youngest person to be invited to join the British Society of Cinematographers. Has the speed of his recognition made him a little wary? McGarvey is engagingly low-key about his career and in some puzzlement he says: ''I never thought I would end up doing this.''

On any movie, of course, the good cinematographer realises that the power he has to shape the mood and appearance of a film is best delivered discreetly - if only for the basic reason that many anxious egos are involved, with most stars insisting they alone know how they want to look before the camera.

But what happens if vanity threatens to sabotage the set? ''Well, you know, I've been really fortunate in my short career so far. I've worked with truly brilliant actors and actresses and their first concern has always been one of characterisation and the role. Having said that, you can't just light Meryl Streep as if she were Bella Lugosi. You have to be sensitive when the public knows a particular actress as being very beautiful.''

Yet is he saying that vanity never plays havoc during shooting? McGarvey laughs and raises a droll eyebrow. ''Actually I have met actors who are far more vain than the most stunning looking actresses, and then it can be a tussle of wills between the director and the star.''

McGarvey is far too courteous and wise to name any offenders. Some directors do try to fight it but it's usually futile, and if an actor isn't comfortable then the performance will suffer. So it's in everyone's interest to make sure the actor feels at ease. Not that you are acceding to vanity.'' He raises that eyebrow again.

''On The Hours, where we had three of the world's top actresses - Nicole Kidman, Julianne Moore and Streep - there was absolutely no problem like that. Obviously it was tricky filming Nicole with that nose. You had to be very careful about the type of light used. Side-cross-light would have picked out the edges of what was, after all, a very significant prosthesis.''

Indeed, McGarvey never saw Kidman without that Virginia Woolf ''nose'' until about halfway through the shoot when she threw a small party for the crew. ''It was bizarre walking into a room with Nicole, entirely herself, saying 'Hi'. I was completely taken aback by the transformation.'' But for Kidman, still bruised at the time by her acrimonious divorce from Tom Cruise and the paparazzi's persistent stalking, that nose had its uses beyond the set.

Once during location in Richmond she wore it out on the street and the disguise was so effective the Daily Mirror ran a picture of the film's director talking to her, with the caption: Stephen Daldry with an extra from his new movie, The Hours.

As a teenager McGarvey intended to read French at Edinburgh University but a family friend who had observed his increasing gift for photography encouraged him to pursue it as a vocation. ''So I found myself at Central London Polytechnic, where I decided to study film. But when I left it was the usual thing of starting at the bottom, trying to pick up work as a camera assistant or as a clapper-loader. I have to admit, though, that for a couple of years my main occupation was painting and decorating to earn what money I could.''

The initial break came when the radical British director, Michael Winterbottom, saw one of McGarvey's shorts, Floating, which had won an award at Cannes. Winterbottom signed him as the cameraman on his low-budget, gritty Butterfly Kiss, a road movie set in and around Liverpool with Saskia Reeves and Amanda Plummer. Then followed a batch of television documentaries and by 1997 he had landed the job of cinematographer on the elegiac movie, The Winter Guest, starring Emma Thompson and her mother, Phyllida Law, and directed by the actor, Alan Rickman.

He was also picked that year by playwright and artist John Byrne to film his anarchically comic Slab Boys. That is where McGarvey met Phoebe, his wife and the daughter of that valiant and enduringly independent Scottish filmmaker, Murray Grigor. ''Phoebe was working on Slab Boys, which we shot in Glasgow. It was a very platonic relationship, but we kept in touch when the movie was over. Or rather, I pestered her for a long time and finally she gave in and married me.'' Which is how McGarvey comes to be living in Edinburgh, Phoebe's home time, with their three-year-old daughter, Stella.

Despite its recent international laurels, The Hours was actually made more than three years ago and McGarvey will soon be working on his fourth film since then. Among his commitments is his father-in-law's new opus which will revive Murray Grigor's early collaboration with Sean Connery in a series of cultural documentaries about Scotland. Ranging from the mythological to the contemporary, each episode will be observed unsentimentally by Grigor's serious but often irreverent eye.

McGarvey describes his favourite style of cinematography as almost invisible, the kind that melts into a film without drawing attention to itself. His own work on that harrowing TV movie, Wit, is the perfect demonstration. Directed by Mike Nichols, it portrayed Emma Thompson as an esteemed academic with terminal cancer, and with great delicacy McGarvey's camerawork drew the viewer into the drama. ''The French talk about stitching the audience into the picture so they are woven into the plot rather than being deflected from it by lots of zippy momentum and dynamism in the cut.''

His heroes are Chris Menges, the cinematographer on The Killing Fields and The Mission and Sven Nykvist who worked with Ingmar Bergman. ''It must have been wonderful to work with Marlene Dietrich and have been told by her where to position the key light.''

So, how does he explain the magic about the camera loving certain faces? ''I think it's in the eyes really. Some actors just light up on screen. I've done two movies with Julianne Moore who is famous for performances where she doesn't say much but she is luminous and powerful in every role. Someone you could easily walk past in the street but once the camera is on her she is a star.''

In the end, though, Seamus McGarvey is the first to concede that the real magic of film defies explanation. There are times when everyone on screen knows it is the exceptional cinematographer who is the essential wizard, the one player who can make the whole business of make-believe glow.

CV: Seamus McGarvey

Born: Armagh, 1967.

Education: Christian Brothers Grammar School in Armagh; City of London Polytechnic where he studied film.

Married: Phoebe Grigor in 1999; they have one child, Stella.

Career: Began shooting documentaries and shorts which included Skin starring Ewan Bremner, of Trainspotting. Other major titles include Enigma, Wit, A Map of the World, High Fidelity, and the multi-Oscared, The Hours.

Highs: ''Meeting Nelson Mandela when shooting Jump the Gun, the first major movie to be made in South Africa after the abolition of apartheid. And being at a party in Belfast the other night where Seamus Heaney was present, the great man of literature having a drink and a laugh and reciting a funny little verse called Piddling Pete about a dog and a lamppost.''

Lows: ''The death of my father. He was just 52 and I was at that age when you start having a proper adult relationship with a parent and suddenly they are gone.''