IN THE PACK of news photographers who swarm around just about every public happening in Washington, there's likely to be one whose efforts to capture images of the fleeting event seem just a little less frantic. As the others crowd in, this man or woman may step back and take pictures of the people taking pictures of the people making news.

This tendency to take the long view is the trademark of the photo staff of the Smithsonian's National Museum of American History. They're not seeking to capture moments so much as to assemble a record of events along and around the Mall, and the audience they're aiming for isn't tomorrow's newspaper reader but future generations who seek to know the texture of our era.

A sample of what they'll see will be on view on the museum's lower level through November. Most of the 53 photos look as though they might have come from a press association exhibit; some, such as Jeff Ploskonka's portrait of a pensive lad atop the Vietnam Memorial, would very likely win prizes.

Some 40,000 frames have been exposed since the project began in 1976. That sounds like a lot, but amounts to only a fraction of the number of pictures a major newspaper's photo staff will take every year. But the Smithsonian's negatives are described, catalogued, cross-indexed and protected from deterioration; most unpublished press film soon becomes irretrievable or unusable.

Other than bringing to the job a special sense of duty to the historical record, the Smithsonian's photo people generally use criteria and techniques -- and get results -- very similar to those of press photographers.

"We try to include the physical setting as much as possible," says James Wallace, chief of the museum's printing and photographic services. "We may be fascinated by the crowd at an event, but somebody in the future might be more interested in the plane in the background, or the age and condition of the trees behind the speaker's stand." HISTORY AS SEEN FROM THE MUSEUM -- Through November at the National Museum of American History.