BOOK REVIEW / NOVEL : Filmmaker’s Change of Venue Still Has Cameras Rolling : ROBINSON <i> by Christopher Petit</i> ; Viking $20.95, 204 pages

Since this darkly atmospheric story of corruption and collusion, sex, decay and violence is the first novel by British filmmaker Christopher Petit, it’s natural to wonder what “Robinson” would be like as a movie.

Especially because it’s about movie-making--at least that industry’s low-budget, X-rated fringes. And because one of its themes is that “experience and memory (are) no longer enough” for us now that video technology has made it possible “to have a personal visual souvenir. Being able to . . . turn everything into television . . . (provides every act with) its own absolution.”

Even murder.

Petit’s writing is sharply visual, as we might expect. He has a scenarist’s ability to sum up a character with a few words and gestures. He packs a great many incidents into a small space. Yet the novel’s main strength--its exposure of the narrator’s self-deception as he is drawn into the orbit of the sleazy and seductive stranger named Robinson--is the strength of words, not of images. And the excesses that weaken the ending are literary, too.

The narrator is a burned-out film editor in London’s Soho district. Robinson is a wealthy pub-crawler, seemingly without an occupation or a past. The narrator is alarmingly vulnerable to his suggestions: On a drive together, he nearly runs down a pedestrian at Robinson’s urging. More than once, he suggests that Robinson is his alter ego. “That was his skill: to show you parts you carefully hid from yourself.”

Even away from Robinson, however, the narrator lives a life of controlled recklessness. He drinks too much, experiments with opium, frequents porno theaters, sleeps at the office and later in Robinson’s vacant apartment. He gradually abandons even a pretense of domesticity. When his wife leaves, Robinson reels him in--first to work in a bookstore, then to help produce skin flicks with a cast of misfits recruited from the streets.

The actors are “victims of recession who in better times might have gone to art college or become musicians . . . young, good-looking and, for all their air of worldliness, ripe for exploitation.”

Despite his dominance, Robinson is a slave to the same appetites he manipulates in others. He grows fat and dependent on drugs. Obsessed with “power, pain, pleasure, and their exercise,” he gets bored with filming orgies and begins to pick up homeless people, torture them and film that.

And despite his evil propensities, Robinson is in some sense an artist (which throws art itself in a dubious light). The narrator believes--although we may not--in the sincerity of Robinson’s search for the “one shot that, when placed right, would illuminate and give meaning to all the others.”

Petit’s achievement in this novel is a kind of double vision. The narrator sees without really seeing. His fall follows the stark and simple trajectory outlined in every Sunday sermon, but he distracts himself (and us) by doing somersaults as he falls.

We see--although the narrator doesn’t quite--that his life turns inside out. At first he hides his Soho escapades from his wife; later he hides his attempt at reconciling with her from Robinson. At first he views Robinson, with distaste, from the outside; later he becomes Robinson--trying to finish his films and appropriate his vision.

The novel form helps Petit get away with this. His crisp and elegant prose filters the narrator’s experiences as only the most radical camera work could. He is able to shut out the normal world almost completely; he can render sordid events as grotesque, comic.

This would be harder to do in a movie. The camera, for all its power of illusion, is also a reality check. The narrator’s wife and Robinson’s victims would arouse more sympathy if they had the faces of real actors. A filmed London, however moodily shadowed, would refer constantly to the real one.

In the end, the conflict between the narrator’s intelligence and the depth of his delusion gets to be too much for Petit. He conjures up an apocalyptic ending in which a flooded, crumbling England mirrors the narrator’s mental state. This would cost millions to film, but it’s easy to do in words--in this case, a little too easy.