ALTHOUGH cinema is less than a century old, it has a rich and complex history, not all of which has been thoroughly explored. One pocket of film activity that has been largely overlooked is the production of Yiddish-language movies in a number of countries, from Eastern Europe to the United States, beginning in the glory days of silent cinema.If film experts have often failed to give Yiddish movies their due, however, this doesn't mean Yiddish-speaking audiences have neglected them. Pictures with Yiddish dialogue have been in continuous distribution since the 1930s. "They're remarkably resilient," says J. Hoberman, a critic who has devoted much time to the subject. "Considering how many old movies have disappeared, it's amazing how many Yiddish films remain." They're receiving a new and important boost from a show called "Yiddish Film Between Two Worlds," running through Jan. 14 at the Museum of Modern Art here, and then traveling to Boston, Berkeley, Calif., London, Jerusalem, and other locations. Billed as the first major exhibition of Yiddish films made in Europe and the US from the '20s to the '80s, it arrives concurrently with a handsomely produced study by Mr. Hoberman called "Bridge of Light: Yiddish Film Between Two Worlds," published by Schocken Book s and the museum's press. The show is coorganized by the National Center for Jewish Film in Waltham, Mass., which circulates many of the films to the public on video. Yiddish filmmaking grew out of the once-bustling world of Yiddish theater, and many Yiddish movies have a stagebound and somewhat "uncinematic" look about them - sometimes using dialogue, for instance, to convey events that Hollywood-type movies would depict in images. Some aspects of their acting and camera styles may appear dated today, though these surely seemed vital when they were new. What compensates for such limitations is a sense of conviction and even passion that surges through the best Yiddish films. Often their subjects are as emotionally timeless as they are historically specific: mixed feelings over assimilation into non-Jewish cultures, conflict between generations over Americanization, anguish at seeing traditions overtaken by modern times. Yiddish filmmakers found numerous ways of approaching these and other highly charged topics with deep-rooted sincerity. Bearing in mind that Yiddish movies have been made in several countries over a period of several decades, I recently asked Hoberman what characteristics he considers typical of Yiddish cinema as a whole. He mentioned three: a close relationship with the tradition of Yiddish theater, enduring popularity, and a tight connection between the subjects of the films and the concerns of their audiences. "People rarely set out to make Yiddish art films," Hoberman says. "These films were brought into existence by the mass audience that existed for them. I've sometimes called Yiddish film a 'folk cinema' because it's a small-scale cinema, made by artisans who weren't that separate from their audience - as opposed to the big industrial machines of Hollywood filmmaking. Some high-minded individuals did get involved in it, and some of the Soviet films certainly had a political agenda. But by and large, the fi lms followed audience taste rather than molding it." The appealing simplicity of many Yiddish films can be traced to the audience they sought. "Yiddish has traditionally been a language of poor and working-class people," Hoberman says. "As with early film in general, the first audiences for Yiddish film were not middle-class. But while Hollywood film moved upward to more well-off audiences, Yiddish films didn't.... "At the same time, Yiddish has always been a language for 'insiders,' and this caused controversy around some Yiddish films. Movies are more public than theater, and some people worried they would be too accessible to gentiles." Essential to the enduring value of Yiddish films, Hoberman says, is their ability to function as a "public sphere" of Jewish culture and belief. "It's difficult to reconstruct what the Jewish world was like before Israel existed," he notes. "Theater occupies a physical space, and so Yiddish theater functioned as a sort of 'homeland' for Jewish people. Movies picked up some of that function.... Yiddish film has always been a kind of cherished novelty, a source of eternal pleasure, no matter how crummy the print or how sentimental the movie itself." Hoberman's fascination with Yiddish cinema, which dates back more than 20 years, is a natural extension of his interest in all sorts of independent film, from the little-known tradition of African-American cinema to avant-garde and experimental films. As a critic and curator, he says that a realistic perspective is needed for present-day evaluation of Yiddish cinema - avoiding false idealizations. Movies produced in bygone years and in a minority language are still very much alive. "I think the films hav e been sentimentalized," he says, "as Yiddish culture in general has. I've tried my best to make people aware of them as films produced by young people, as a contemporary experience. They weren't made to be old-fashioned. They were made to be modern!"