Sterling Tucker, with more campaign money than any of his rivals in the Sept. 12 Democratic mayoral primary, is starting his television advertising campaign this weekend and at first glance the ads seem aimed at old movie buffs, bowling fans and people who like to watch TV stars in gimmick sports contests.

The 4 1/2-minute Tucker ads, which among other things show the candidate as a civil rights activist, a man concerned with the plight of the elderly and one who eats breakfast with his wife and daughter, are planned to run between 20 and 25 times on local television stations during the next four weeks.

The mini-documentary ad produced at cost of $18,800 and put on the air for another $30,000, is unusual, not for its content, but rather for its timing. Candidates usually do not buy expensive television advertising three months before an election unless they are not well known. But Tucker, the District's City Council chairman, has a high name recognition, various polls have shown.

"We have a long-range plan it calls for some (advertising) now and some more later," explained campaign spokesman Sherwood Ross. "When you have a lot of undecided voters, it's better to go after them early."

A Washington Post poll taken June 1 to 5 showed Tucker leading with 24 percent to 20 percent for Mayor Walter E. Washington and 18 percent for council member Marion Barry. But the poll also showed that 35 percent of the 1,020 registered Democrats interviewed said they were undecided.

"There are probably going to be 110,000 to 115,000 people voting in the primary," said General Wallete, Tucker's campaign manager. "We can't shake every hand. Television is designed to reach them."

Barry and his campaign manager, Ivanhoe Donaldson, have a different view of why Tucker is putting ads on now.

"He's scared ." Barry said of Tucker. "That's what candidates do who are unknown. He's slipping; he has to shore up the troops.

"We're going to do some (television advertising), but certainly not in June or July," Barry said.

Donaldson added, "It's trying to create an illusion of activity and visibility. Given their nervousness, in their shoes, I might make the same decision."

But he also noted that the Tucker campaign, which had raised more than $127,000 as of last Monday, is better able to afford the ads at the moment. "We don't have Sterling's budget flexibility," Donaldson said.

The Barry campaign had raised about $105,000 as of last Monday.

Asked about the timing of the Tucker ads, Mayor Washington said simply, "I can't run his campaign."

The Tucker ad was produced by Bailey, Deardouf & Associates, Inc., a Washington political advertising firm normally associated with such Republican candidates as former President Brooke of Massachusetts and Charles Percy of Illinois.

The ad is scheduled for its first public airing today at 3:55 p.m. on WTOP, Channel 9, just after a 1971 movie called "To Find a Rainbow" and just before a gimmicky sports show called "All Star Anything Goes." The latter offering today matches stars from "The Waltons" and "Eight is Enough" in a contest of made-for-TV sports.

On past All Star shows contestants have performed such stunts as piling as many inner tubes as they can on top of one person. About 53,000 people can be expected to be watching at the time of the ad WTOP said.

The Tucker camp plans to show the ad again tomorrow at 1:55 p.m., when about 75,000 to 80,000 people may be watching WTOP, just after it airs a 1959 movie, "It Happened to Jane," and just before a bowling championship. Later showings will be spread throughout the day, including some near prime evening time, according to an advertising official who placed the ads.

The ad starts with a film clip of a group of ministers endorsing Tucker last month, recites his civil rights activism in the 1960s and then shows hi in a variety of scenes filmed talking to prospective voters.