Optimism and hope were tempered by weariness and a touch of cynicism last night as a candlelight vigil for the hostages held every Sunday in front of the Iranian Embassy swelled from its usual handful of participants to include more than a hundred persons.

There were only three hostage relatives huddled with the group across-Massachusetts Avenue from the dark and empty embassy. The rest included newcomers, a few out-of-towners who drop by whenever they are in Washington and a core of regulars who are there just about every Sunday, rain or shine.

For all these people, the crisis has been more than just television pictures from far away, more than newspaper articles, more than yellow ribbons faded and torn from a year's exposure to the elements. To them, they say, the hostage crisis has been grueling, and personal, and above all something that demanded involvement.

The vigil "just seemed like something that needed to be done," said Linnea Chilstrom, a Philadelphia woman who first saw it on television several months ago and now makes it a point to attend every time she is in town. She made a special train trip yesterday to be here to commemorate the upcoming one-year anniversary of the taking of the hostages, unaware of the developments of the weekend that have spurred hopes that the hostages may soon be released.

Chilstrom, who does not know any of the hostages or their families, said she is hopeful of an early release. She, like many of those present yesterday, does not believe President Carter has tried to manipulte the crisis to better his chances of winning Tuesday's presidential election.

"That's a terrible thing to accuse a human being of," she said. "The thing is just to get them out. They are our brothers."

Others, such as George Kalin, were a bit more cynical. "There's no doubt that it's politically timed," he said. While Kalin said he was not sure whether Carter had tried to maneuver the situation for political gain, he is convinced that the Iranian government is trying to help Carter reman in office. Iran would prehaps stand a better chance of obtaining military parts and supplies needed to wage its war with Iraq from a Carter administration, Kalin reasons, than from a Ronald Reagan administration.

"I hope the American public doesn't allow this to happen," Kalin said. "We all become hostages if we allow Iran to dictate to us who we vote for. I hope people are able just to vote their conscience on Tuesday."

Kalin, his wife and two daughters make the 70-mile trip from their Hagerstown home every Sunday to join the vigil. "It's just a small gesture," he said. "This is about all a private citizen can do. We just want to keep the situation in the limelight as long as we can."

A visit to the vigil from a hostage relative is a special occasion, and when Penne Laingen -- wife of U.S. charge d'affaires Bruce Laingen, the highest-ranking of the American hostages -- arrived yesterday, she was greeted warmly.

"I'm hopeful that this is the begining of the end," she said. "I think the Iranians really want to get this settled. They perhaps don't know just how to go about it yet." Laingen said it was important to her and her husband that the United States settle the crisis "with honor."

John W. Limbert, father of hostage John W. Limbert Jr., was even more guarded in his reaction to events of the weekend. "I'm not cheering or jumping up and down," he said. "I've been on this yo-yo before. It just takes too much out of you. Your nerves get too frazzled."

Joe Keyerleber, a General Accounting Office Worker, helped organize the first vigil last Thanksgiving and has been coming ever since. He said this Sunday's gathering was expected to be larger than normal, because of the upcoming anniversary. But like everyone else, he had no idea that events on the other side of the world would change the picture so dramatically and multiply the group's normal ranks tenfold.

But no one was willing to go out on the emotional limb, to believe openly that after so long, the crisis was ending.

"If we have to come back next week," said Kalin, "we will."