Diedre Ware of Alexandria spent $20 and five hours last Saturday for a chance to see herself on national television this summer.

If the hopeful actress is lucky, she may get a glimpse of the back of her head in a 37-second section of an hour-long television documentary filmed in Old Town Alexandria.

But Ware did not mind the expense of renting her blue and white-aproned colonial costume or the time she invested. She was a volunteer extra in the film because she is interested in acting as well as in the film's subject, Benjamin banneker.

The son of a freed slave who lived in 18th century maryland, Banneker's life is the topic of a film being produced by Cine-Men Productions of Baltimore. The $100,000 project was commissioned by The Catonsville Historical Society and the American Bicentennial Committee of Catonsville, Md.

A self-educated man with a passion for astronomy and mathermatics, Banneker is probably best remembered for his part as an assistant to Andrew Ellicott in the first survey of the District of Columbia in 1791. In that effort, he was also an assciate of Pierre Charles l'Enfant.

During his lifetime Banneker was also cited frequently by abolitionists as an example of what blacks freed from slavery could accomplish.

The group played a Quaker congregation listening to a pro-abolition speech by the cchurch minister, played by Joe Clair.As Clair delivered the remarks, using Banneker as his example of the black man's intelligence, the camera panned out from the pulpit, down the historic church's center aisle to show the congregation.

Some participants, such as Michael and June McInerney of Alexandria, wore authentic, handmade costumes used in many of last year's Bicentennial events. Others, liek Washington resident Pamela Jones, scavenged through closets for their get-ups.

"I am very pleased iwth the way they look," film producer and director of photography Jochen Breitenstein said. "These things are hard to predict."

The "congregation" began filing into the church slightly behind schedule at 10:30 a.m. and sat through more than an hour of camera problems, lighting adjustments and seating changes "so the better-looking ones are more visible," Breitenstein said.

Shortly, after noon, the camera began to whir quietly. After Clair finished his brief speech and director Leroy Morais called out "cut," there was an audible sigh of relief from the crowd.

By the fourth try, the group began to loosen up. Several children enjoyed a sack lunch between the fifth and sixth shootings and former strangers sitting side by side began to chat freely by the seventh.

"I think it was marvelous," said Louise Yamber of Arlington. "I was impressed with the variety of costumes. We had the whole colonial period."

"It surprised me how much time they spent filming," Seymour Young of Alexnadria said. "I didn't think for a 37-second stretch they would spend that much time. No wonder movies cost so much."

Not all the participants were satisfied. Among the disappointed were members of the Quiet Fire Repertoire Company, Inc., an acting group in Arlington.

"This scene is broing to me," group member Trina Price of Arlington said. "I thought we were going to be doing something."

Breitenstein said the filming will continue for several weeks in the Ellicott City, Md., area before the editing begins. He expects the final product, to be entitled "The Man Who Loved the Stars," to be aired in early summer on WMAR-TV in Baltimore and on PBS nationwide.