Brian Marchetti knows all about the image problem.

"Most people think of opera as women wearing big hats and horns who break glass as they sing," says the 11-year-old from Clifton. "But there's a lot more to opera. It's really beautiful."

Brian was converted to the art form thanks to a month-long camp run by the Washington Opera for ages 10 to 14. The program at the Kennedy Center combines performing a short one-act opera with field trips to visit professional performers.

The end result, hopes camp director Debra Evans, who started the program five years ago, will be a new generation that appreciates and understands opera.

But at the moment, the immediate goal is putting on a show.

"The price of talking during arias is expulsion from the room," bellows Molly Haws, production and stage manager, to the chattering group in the rehearsal room. Silence falls like a brick.

"The common thread" among the 34 youths in camp, Evans says, "is that they all enjoy singing and performing."

Outside, the sun blazes, and back in Warrenton her friends are spending the day at the pool. But Bess Coxsey sits on the hard floor of a windowless rehearsal room, waiting for her cue. She's an ensemble member in Cary John Franklin's children's opera, "The Thunder of Horses."

Although she's never seen an opera and her radio dial stays tuned to classic rock stations, Bess, 13, says she doesn't miss the pool one bit. "I don't like opera to any extent, but it's an interesting experience," she says. "I want to be a singer, just not an opera singer."

A seasoned performer at age 12, Dara DeMarsh Laos has been taking singing lessons since she was 6. She recently entered a modeling contest and spends all her free time during the school year performing in musicals.

She hopes opera camp will broaden her singing horizons and build her resume. But although Dara says she has learned a lot, she confesses to a pinch of disappointment in the level of commitment from other campers.

"I see three or four people in there besides me who are very dedicated," says Dara, who car-pools 45 minutes to and from class each day from Stafford. As for the rest, "the Kennedy Center is not a big deal to them. Me, on the other hand, I think the Kennedy Center--wow!"

Last March, 60 youths from the region auditioned for the camp. This year's group is the largest ever, nearly equally boys and girls. About one-third of them are back for a second summer.

The program costs $1,000, and about one-third of the campers get financial aid.

Although most opera companies do extensive outreach programs during the school year and several offer summer programs, few are as intense as the Washington Opera's program, says Samuel Smith, director of media and audience relations for Opera America, a national association of the opera community.

None of the major national companies--the Metropolitan Opera, the Chicago Lyric Opera and the San Francisco Opera--has summer camps. Closer to home, the Levine School of Music has two similar programs during the school year.

"We try to get them before they have preconceived notions of the art form," Evans says. "Opera is basically a story that is told through music. Add the visual elements of props and sets and kids are transported to a magical world."

Twelve-year-old Jamol Johnson, of Washington, heard about the camp from his singing teacher. To Jamol, the most fascinating aspect about opera performers is "how they can concentrate on their movements and sing at the same time." At one recent rehearsal, he also experienced the less glamorous side of performing--all the repetition and waiting around.

But he says he doesn't get bored. "I may look like it," he says with a slight smile. "But I'm not."

"The Thunder of Horses"

will be performed today at noon and 2 p.m. at the Trapier Theater of St. Albans School for Boys, Wisconsin and Massachusetts avenues NW. Composer Cary John Franklin will give

talks before each of the

free performances.

Information: 202-295-2420.