For his first invitation-by-card-only art preview and evening reception, 19-year-old Lee Jaffe donned his unpressed white painter's pants and the cheap derby hat that he had bought from a street hawker and went to the Hirshhorn Museum last night.

There Jaffe, whose home is in New York City, stood in front of one of Richard Estes' urban landscapes, looking up Broadway from Times Square.

"I'm afraid I'll get run over if I get too close," said Jaffe. "It's so real."

For the unabashed eavesdropper-at-art-exhibits, it didn't take long last night to determine that the talk was quite different from that overheard at most of the city's many art previews.

No one was explaining nonobjective art or debating minimal representation or discussing abstraction.

"He can draw. That figure of the woman crossing the street could be a photograph," said one professional photographer in the ultimate tribute from him for an artist.

The Hirshhorn exhibit, which opens today to the public and runs through April 1, features 30 paintings by Estes, a hyper-realist among present-day American painters, who finds beauty in urban landscapes of luncheonettes, storefronts, escalators, telephone booths, and street scenes of big cities.

"See how he handles the light and sky. And he places the cars on the street to guide your eyes. He doesn't just find them. Otherwise, it would just be a good photograph," a woman was explaining to her companion as they studied "Valet," one of the artist's New York street scenes.

The preview guests last night could follow Estes' work from the mid-'60s through "Gifts of Nature," a painting just completed by the artist and seen for the first time in Washington. In the later work, his style has become increasingly precise and pristine.

One of the games last night was spotting the artist's name or initials in the paintings, whether on a coffee shop menu or a marquee or a tattered poster on a lamppost.

Estes, in a brown velvet suit, arrived late for the 9-to-11 p.m. reception from a dinner at the home of collector Robert Kogod, who lent one of his paintings, "Escalator," for the Hirshhorn exhibit.

Wandering around with the 400 other guests. Jaffe obviously was enjoying his first formal art exhibition. He is in Washington on a work-study program from Antioch College in Ohio, where he met Scott Pollock, whose mother is a docent at Hirshhorn.

"You may say this may be my first but won't be my last art preview," said Jaffe. "I think quite a few came for the stuffed mushrooms."