Beantown: new focus of cameras from Tinseltown

''There she is,'' exclaimed Daniel Webster, speaking of Massachusetts in 1830 . ''Behold her, and judge for yourselves.'' A century and a half later, America's television executives seem to have followed Webster's advice. They have judged the Bay State - and taken it to heart. Next fall, no fewer than four network series may use the Boston area as a backdrop for their stories.

''I can't think of any other time in the TV industry when four - or even three - TV series on the air in their first run were all set in the same city, outside of Hollywood or New York,'' says Roger Burke, assistant director of the Massachusetts Film Bureau.

Many television viewers are already familiar with ''Cheers,'' a comedy set in a Boston bar, and ''St. Elsewhere,'' a hospital drama, both of which premiered last fall. In the works now are two more series. ''Goodnight, Beantown,'' a comedy-drama about a local TV news team, makes its debut this Sunday. ''Spraggue ,'' a TV movie about the adventures of a Tufts University professor-turned-detective, is being shot now. Both could show up on the regular fall schedule if well received.

At least one media executive says the current trend could mean big things for the East Coast state. ''Massachusetts has the potential to break the New York-California grip on TV and movie production,'' says Bob Bennett, senior vice-president of Metromedia Producers Corporation. His firm recently purchased BBI Productions, a Massachusetts company that produces syndicated TV shows such as ''This Was America,'' ''The Body Works,'' and ''Tom Cottle Up Close.''

Is it cobblestone streets, ivy-covered universities, or ethnic charm that brings cameras to the state?

Only in part, says Mr. Burke. The Massachusetts Film Bureau, a state agency set up in 1977, also tries to convince filmmakers that the state is ready to help them by cutting bureaucratic red tape. His office offers ''daily, even hourly'' help in dealing with local cities and towns, and in finding local talent and support services such as rental equipment and caterers.

When the makers of the movie ''Yes, Giorgio'' needed a crowd for an outdoor concert scene awhile back, the bureau helped to arrange a special concert at the Hatch Shell on the Charles River. About 100,000 local residents served as ''extras.'' More recently, the filming of ''Spraggue'' was snagged when a fountain in Copley Square would not work. The bureau arranged for a fire department hose to create the proper effect.

This kind of cooperation is helping the state shake ''the East Coast reputation of being expensive, with tough unions,'' Burke says.

The economic stakes are high. A feature film crew spends up to $75,000 a day when working on location. Much of this money ends up in the hands of local actors, hotels, restaurants, and merchants.

Surprisingly, because network TV shows are shot mostly in Hollywood studios, with only a few ''exteriors'' on location, they are not as lucrative as some lower-budget projects.

TV shows and movies such as ''The Verdict'' - an Oscar nominee that was among 16 feature films shot in the state last year - may gain the most attention, but local film companies are the real ''bread and butter'' industry for Massachusetts, Burke says. These independents, who usually make documentaries, commercials, and industrial films, earned $27 million in 1982 and employed 850 people.

Because of a strong local industry, the state has the best behind-the-scenes services for film crews outside the Los Angeles-New York centers, Burke says. For example, a filmmaker was recently able to rent $50,000 in special lighting here instead of bringing it in from out of state, he says.

Although it's nice to be thought of as scenic or historic, Massachusetts must be more than just another pretty place, Burke says. ''A film can be 'cheated' anywhere,'' he says, referring to the uncanny ability of filmmakers to make southern California look like almost any place in the world.

''The main thing is, can you shoot it on budget?'' Burke says. Because film crews who have worked here have spread the word, ''We're one of the first places people think of.'' Even so, the bureau continues to monitor trade journals to ferret out new productions. ''We contact them and say, 'Maybe you could shoot it here?' ''

Finally, filmmaking is ''a nonpolluting industry,'' bringing money, not factories, into the state, Burke says. So, it's likely the citizens of Massachusetts won't mind a bit if their state becomes the land of the cod, the bean - and the videotape.