SAME TIME, NEXT YEAR -- Aspen Hill, K-B Bethesda, K-B Fine Arts, Loehmann's Plaza I, Springfield Mall Cinema, Riverdale Plaza, Tysons Twin I.

Mechanically, "Same Time, Next Year" is a perfectly disciplined stage comedy. The play requires only two actors and one set, but encompasses a range of development, both in the characters and in the times they live in.

As a film, it suffers from too much freedom. With the vast amount of space available to the camera, the movie version looks stingy when it keeps to the stage limitations, and redundant when it goes beyond them.

However, Bernard Slade's story still has its tender and funny little theme, and there are two good actors, Ellen Burstyn and Alan Alda, doing well by it under the circumstances.

The cirumstances are more difficult on film than on stage, because the story takes the characters through 26 years, in which they not only age but succumb to the various fashions of each period. Booth Tarkington once wrote that the end of gaslight was ruining the acting profession because the electric glare limited actors to characters of their own ages, but this is twice as true of film.

The story opens in 1951, when a young married woman on her way to an annual religious retreat meets, in a country inn, a young married man who is on an annual business assignment. First they go to bed, and then they become acquainted.

The affair turns into an annual event.Scrupulously out of touch during the year, each shows up in the same place at the same time year after year. They are strongly good-hearted people, but both very impressionable, and their responses to the spirit of the times they move through make a catalogue of popular culture. One year, she shows up in Indian fringework to discover that he has become a Goldwater Republican with a three-piece suit to match; another, she's a polished businesswoman, while he's freshly loosened up from encounter groups.

Burstyn's characterizations range from Pillsbury Bake-Off to nouvelle Betty Ford; Alda's are more dependent on the amount of gray in his hair than on emotional evolvement. But the essential likability of the pair, along with the era-reflecting dialogue, carries them through.

Delicately suggested by the cliches of clothing and conversation, the pattern of the years is charming. But the filmmakers have all but clobbered it to death with unsubtle techniques, ranging from a dreadful background theme song, in which Johnny Mathis and Jane Olivor belabor a gentle idea into stupidity, to montages of nostalgia photographs, dominated by the images of Elvis Presley and Richard Nixon, reducing the passage of time to a collection of fads.