John Bailey has a problem. Or rather, had one.

It happened two days earlier, in Chicago, where he's working on a film called "Light of Day." And it happened in a bathroom.

"We had a sequence in a very low-ceilinged, claustrophobic men's room downstairs in an auditorium where a rock concert was taking place," he remembers. "There was no place to hide lights -- it was basically a long narrow room with open urinals and a couple of stalls, and I had to light the length of it.

"Ideally, your lights come from the side and from behind, and you just fill a little bit from the front. So I taped a couple [of] lights to a wall, flat fluorescent lights that were just out of the shot. And I tried to bounce some light off the ceiling at a rake angle, so that it kicked down on the actors.

"That's one of the most difficult lighting jobs I've ever done, a half-page scene of two guys walking up to a urinal."

When "Light of Day" opens next year and you see the credits, you'll recognize the names of "Back to the Future's" Michael J. Fox and rock star Joan Jett, who are the stars, and of Bruce Springsteen, who wrote the theme song, and maybe (if you're a bit of a film buff) of director Paul Schrader.

And you'll see the name of John Bailey listed as "Director of Photography," known variously in the trade as the cinematographer, the cameraman, the D.P., and although he's the second most important man on the set, you'll wonder what that means, and who he is, and what he does.

What he does is go to the set every day, and, with the tools of his trade, the inkies and arcs, HMIs, brutes and minibrutes, 2Ks and 10Ks, the white cards and photofloods and chicken coops, makes scenes like the one in the bathroom look not difficult at all -- look, in fact, just like two guys walking up to a urinal . . .

At 43, Bailey enjoys a reputation as one of Hollywood's half-dozen or so premier cinematographers, and the favorite of the New Hollywood. He's shot every one of Schrader's films since "American Gigolo," every one of Lawrence Kasdan's since "The Big Chill"; he shot "Crossroads" for Walter Hill.

Films are images. Images are light. And John Bailey is the master of light.

The biggest lies are the most successful ones, and in the film business, which is a business of lies, the biggest lie of all is the auteur theory.

Films simply aren't the creation of a director the way a book is the creation of its author. They depend instead on a delicate and complex understanding among at least eight primary players: the director, the screen writer, the actor, the editor, the production designer, the composer, the casting director, the cinematographer and (in some cases) the producer.

Of these relationships, the one between the director and the cinematographer is as significant as any. The legendary cinematographer Gregg Toland, for example, is generally credited with creating the expressionistic visual style of "Citizen Kane." Ingmar Bergman became a great filmmaker after he teamed up with Sven Nyqvist; likewise, Woody Allen through his collaboration with Gordon Willis, the finest cinematographer of the modern era.

"I certainly don't like the dictatorial attitude," Bailey says. "It's one of the things that I evaluate when I decide that I want to do a project: Is this director secure enough in his own skin that he's willing to have an open, collaborative experience, or is it somebody who either feels intimidated by the cinematographer, or has no respect for the cinematographer, so that either way he's got to squash him."

Generally speaking, Bailey, as the cinematographer, bears responsibility for the image. Anything more specific than that gets sticky.

With each shot, filmmakers have to make many decisions, which accumulate to determine the nature of the image. Do you use a long lens or a wide-angle lens or a 50 mm lens, which replicates the perspective of the human eye? Do you shoot with the aperture wide open, which leaves the background indistinct, or closed, which makes it sharp? Where do you put the camera, and at what angle? Do you light the shot "high-key," so that light predominates, or "low-key," so that it's mostly in shadow? And on and on.

The composition of the frame -- essentially what people, objects and backdrops are included in it, and in what relation -- is crucial among these decisions. It helps determine, among other things, whether the audience's eyes are drawn to the focal points of the scene, or distracted elsewhere. And it illustrates just how collaborative the process is.

While a great cinematographer can do anything with light alone, good composition generally depends on a rapport between the cinematographer and the production designer. "A brilliant designer can make a mediocre cameraman look very, very good," says Bailey, who has worked with one of the best, Fernando Scarfiotti, on three films. "A brilliant designer is involved in all the elements, not just the sets but the wardrobe, the dressing of the sets."

Still, composition is just one element, and you're back to those thousand decisions that go into creating an image. When Bailey works for an inexperienced director (like Gene Saks, a theater director who hired him for the upcoming "Brighton Beach Memoirs"), he might make all of these decisions, working from the director's general suggestions. In the case of a director with strong visual ideas like Schrader, Bailey's role will be more subtle and complicated -- a combination of sounding board, idea man, cheerleader and technical expert. His only exclusive responsibility would be the light.

The most general misconception is that great cinematography means pretty pictures, when in fact you could turn a monkey loose with an Instamatic and, if he happened to point it in the right direction, get a wonderful image of a sunset. The Academy Award for Best Cinematography is regularly awarded because of people's response to those elements of a film that require almost no cinematography at all (as in this year's award to David Watkin for "Out of Africa").

Gordon Willis, on the other hand, has photographed a half-dozen of the most important films of the past 15 years (including "The Godfather" and "The Godfather II," "All the President's Men" and "Manhattan.") He has never won an Oscar, and has only been nominated once (for "Zelig").

"Post-card pictorialism is what people notice, and a lot of times it's exactly the thing other cinematographers vote for," Bailey says.

The real test of a cinematographer's mastery of light, though, comes in two kinds of situations: "night exteriors," when a scene is shot outside at night, and interiors.

"Night exteriors, where essentially everything that isn't lit is black -- that's the most challenging, the most creative," Bailey says. "When you're inside, furniture and walls and doorways and everything tend to give you perspective and depth, and the colors of the walls and furniture give you separation, even if you light in a very soft-light, flat way. But in night exteriors, if you've got a lot of black in the frame, as you very often do, you really establish your perspective and distance through the quality of the light. And because the spaces you're dealing with are so large, it just takes a lot more time -- technically, it's a lot more difficult."

The central challenge of interior photography, on the other hand, is to create a good image while making it seem as if you hadn't used any light at all, a challenge that is particularly acute when, as in that men's room, you're not in a studio but on location and can't put the lights wherever you want. (Or, as Paul Schrader says: "If you really want to find out if someone's a good cinematographer, just check out any scene in a motel.")

In meeting that challenge, there are two basic rules. The first is "source lighting." The notion is that a scene should be lit simply with an actual light source that is visible in the frame -- a candle, say, or a lamp. If extra lights are used, they should be used in such a way that the light seems to be coming from that source. The light, in short, should make logical sense. As Nestor Almendros, Francois Truffaut's longtime collaborator and a partisan of source lighting, wrote in "A Man With a Camera," "I believe that what is functional is beautiful, that functional light is beautiful light."

The second rule is that there are no rules.

"A lot of cinematographers believe that source lighting is gospel," Bailey says. "I do believe in source lighting, very strongly, but I've done a lot of films -- almost all the stuff I've done with Schrader, for example -- where I've totally ignored it."

Yet an image is not a film, something that's become apparent in the work of directors like Adrian Lyne or Ridley Scott, who formerly worked in television commercials, or in the work of the new crop of MTV-trained directors. In those media, the image really is everything; but when the technique is translated, Bailey says, "the shot stops the film" -- moment by moment, you ooh and aah, but there's no accumulation, no resonance.

"The thing that I feel I bring most importantly to a film has nothing to do with the lighting or the composition or the camera movement," he says. "It's a sense of understanding the basic thrust or dynamic of the film, and how you interpret that with the camera."

Agrees director Lawrence Kasdan: "The cinematographer's skill has a lot to do with what kind of person he is, and not with technical things. You can look in Time, and there'll be a beautiful image of English Leather. Doesn't mean anything. He's gotta understand the material, and understand it in dramatic terms, not technical terms."

That understanding shows itself in the way each shot fits in a sequence, the way each sequence connects with the emotion the scene is trying to convey and the way the sequences together form a coherent whole. Again, the director collaborates in this process to a greater or lesser degree. Equally important, though, is the cinematographer's relationship to the editor -- if the editor doesn't cut the film the cinematographer thinks he shot, or if the cinematographer hasn't shot the film the editor needs, you have a disaster on your hands, particularly for the actors, whose performances are built by these two people as much as by the director.

"A truly wonderful performance can be terribly compromised on the simple level of the camera being where it should, and of the performance being covered at the right side and the right angle, and being cut by the editor in the right place," Bailey says.

Because he weds the image to the story, it's hard to identify Bailey with a particular style. The most you can say, really, is something vague: There's a meditative quality to Bailey's light; it feels alive with thought.

It might be more instructive, instead, to take a look at a few of Bailey's films, at the visual strategies he devised to evoke emotions of the story, and to listen to his own idea of what the films were about:

*"Ordinary People": "[Director Robert]Redford felt he was making a portrait of a privileged but ordinary family, at least from appearances. That was very important to him -- that it looked as if everything were in its place, that everything was proper. Through the photography and the lighting and the movement of the camera I tried to pick a style that seemed to give that feeling: a tranquil, predictable, peaceful and elegant sense of place. Then the emotional disruption was matched by a photographic disruption in terms of the cutting style, the abruptness of the imagery. And the film modulates from warmer to cooler colors."

*"The Big Chill": "The film involved a group of people who were in a very intimate physical space for a 48-hour period, but never really connected, never really got that close. The idea for me, photographically, was to find a way to contain the people physically together, and yet not to make it seem that the real connections were happening. So the sequences were short. They were cut, much of the time, before they ended. The camera never really got close for a long time.

"There's only one scene that gets down to the nitty-gritty, and that's that scene at the end of the picture where Bill Hurt finally pulls everybody apart, and then they all attack him. And in fact, we shot that in a very different way. We used a lot of long lenses, which compress the foreground and background, with the camera pivoting around Bill in different ways, so that even though the other actors were on the other side of the room, perspective-wise, in this rather large living room, there are moments in that sequence where they're all suddenly pushed right up against one another. That's an example of making a choice photographically that tries to intensify or support what's going on dramatically."

*"Cat People": "That film, more than any other film I've done, was a cinematic exercise. Schrader and I looked at a lot of German expressionist films from the '20s. I love German expressionist art, Max Beckmann, Emil Nolde and Kirchner and Schmidt-Rottluff, all those people. The boldness of the colors and skin tones that are green or red. Paul and I talked a lot about taking the formal elements of the German expressionist films and bringing in some of the color palette of the expressionist paintings that had been done just a decade before.

"But the screenplay, very frankly, was just awful. We created a very stylish, interesting cinematic piece, and then found out that maybe that wasn't enough."

*"Mishima": "Part of the film consisted of realizations of three of Mishima's novels, which were done in a very stylized, cinematic way. They were all stage sets, and they were designed by Eiko Ishioka so that each of the three novels had a basic color palette.

"In these sections, I made a very dense negative, so that the blacks would be extremely black. You simply overexpose the negative and then tone it down in the lab, and you don't use any filters that would degrade the black. If you have a really strong black, the other colors in juxtaposition to it seem to have tremendous saturation. If you have a thin black, the other colors look muted and washed out."

You could guess that one reason John Bailey is such a special cinematographer is that, unlike so many other filmmakers, who grew up wanting nothing else and ended up making films that feel plastic, he, like his wife, the highly regarded film editor Carol Littleton, grew up in the humanities.

In a story that should warm the collective heart of the National Education Association and possibly even Albert Shanker, Bailey says he owes it all to a teacher back in the Southern California suburb of Norwalk where he grew up, raised as a Catholic, attending Jesuit schools. "I had an English teacher who gave me a lot of books to read, helped me explore concert music -- I guess he saw something in me, an interest in literature and the arts that I had very little outlet to develop in my family, which is a real working class, blue-collar family.

"I remember one day he told me that he was going to go into Los Angeles and see a Swedish film called 'Wild Strawberries,' and talked me into going in with him. I sat there and it burned into my brain, that opening dream sequence -- I had never seen anything like that before. I sat there mesmerized."

He met Littleton in Florence. He was hitchhiking around Europe; she had been studying French literature in Paris and was traveling with a friend. They conducted a romance, off and on, together and apart, for nearly a decade. "Through most of the '60s, like a lot of people, we were really uprooted. I was in Canada, I was here, I was in the Peace Corps, I was draft-resisting. Carol was traveling in Germany and Mexico and France, studying. We carried on about an eight-year correspondence and an occasional real relationship." They were married in 1972.

Bailey decided to go to USC Film School; his original intention was to study film esthetics and criticism, drawing on his background in literature. But all students were required to take a beginning camera course, and Bailey fell under the spell of yet another teacher. "For me the most interesting and charismatic member of the faculty was Gene Peterson, who taught photography. And his energy and dynamism just kind of washed over me. I wasn't particularly interested then in the chemistry of photography or the mechanics; I was interested in the esthetics of it and how it was achieved, but not enough to really get down in the trench. But I decided that if I really want to learn about film, I've got to learn about the camera. I became addicted to that, and decided to pursue a career."

Like most of the film crafts, cinematography enforces an apprenticeship as lengthy as brain surgery. Bailey worked as an assistant cameraman for seven years, and as a camera operator -- the fellow who actually looks through the lens -- for four. His big break came when Schrader and producer Jerry Bruckheimer hired him to shoot "American Gigolo" in 1979. A year later he did "Ordinary People" for Robert Redford. The movie won Best Picture and Best Director Oscars (typically, the picturesque "Tess" won Best Cinematography), and Bailey was off at a gallop.

Bailey sits in the home he and Carol are remodeling in the Los Feliz section of Los Angeles, way up east in the hills where the old movie stars used to live in the silent film era. He's exhausted, having spent the night shooting "Light of Day" in Chicago, then flying to L.A. for the weekend. Monday morning, he'll be back on the set.

The film is about a brother and sister (Fox and Jett) who break away from their blue-collar, deeply religious family by playing rock 'n' roll, and draws its emotion from Schrader's own experiences with the sickness and death of his mother.

"The other three films that Paul and I have done have been, to a greater or lesser extent, very stylized. But this screenplay is very different. It deals with very fundamental, primal family drama, against the background of a garage-band, primal kind of rock 'n' roll. So we thought it would be really inappropriate to repeat the kind of stylistic formalism that we had done before, because it would submerge the drama.

"So the lighting is less contrived, more simple, more naturalistic. The shooting style opts for extended takes, without cutting. What we're doing is we're mixing a kind of unself-conscious, unstylized camera movement, just a sense of the camera being there, present, recording, with a more traditional way of making a film."

Says Schrader: "I said to him, 'There's only two requirements to work on this film. One is that you work cheap. And the other is that you make it look ugly.' In the dailies, he'll ask me, 'Does this look ugly enough yet?' "

And that, for John Bailey, has got to be the biggest challenge of his career.