"The First Time," the latest comic memoir from the French filmmaker Claude Berri, treats the familiar theme of sex-obessed adolescence with more candor than American counterparts like "Summer of '42," which tend to obscure humiliating realities and confusions in the interest of mellow romantic inspiration. Avid to lose his virginity, Claude Langmann, the 16-year-old protagonist of "The First Time," now at the K-B Janus, blunders his way into sexual activity without being satisfied or enlightened. He's a far cry from lucky Hermie in "Summer of '42." When Hermie scored, the gates of heaven seemed to be opening.

Berri's frankness is partly a function of nationality and partly a function of individuality. French filmmakers have always been more outspoken about sex, and Berri has been more autobiographical than most filmmakers.

In fact, Berri embodied his own follies on at least two occasions, appearing as a naive young husband in "Marry Me! Marry Me!" and as a misguided young family man in "Le Sex Shop." He recovers an earlier autobiographical thread in "The First Time." Berri's real name is Claude Langmann, and this character first appeared in "The Two of Us": the little Jewish boy sent by his parents to live with friends in a remote rural district during the German occupation. Alain Cohen, who played Claude as a child, returns in the role of teen-age Claude. Charles Denner also recreates the role of Claude's anxious, overly solicitous father, a Parisian furrier.

The tang in the material derives from its emotional and ethnic originality. In recalling his adolescent sexual behavior, Berri doesn't spare himself embarrassment. He doesn't stop at mentioning the hot author of his period, Boris Vian, or his resident procurer of pornographic stimulants, his older cousin, Leon. Berri quotes the Vian passages that excited his generation of French schoolboys and shows Claude granting occasional passive favors to perverse cousin Leon, a smut peddler with ulterior motives.

Claude's loss of virginity is not an overnight sensation. It's a cumulative process composed of several messy, inconclusive episodes: nights of self-gratification under the influence of Boris Vian, heavy petting with an obliging classmate, a melancholy visit to a Pigalle professional, a communal romp with a voluptuous hiker that does more for Claude's pal than Claude and an infatuation with a Quebec girl that inspires brief delusions of running away from home in pursuit of a Grand Passion.

Berri's observations of adolescent gaucherie, circa 1952, seem mortifyingly authentic. In addition, the Jewish domestic settings are rare in French filmes. Berri can't be the only French Jewis director, but it seems that way. His casual, affectionate depiction of Jewish family life gives the basic comedy material a distinctive humorous shading. Sometimes the shading recalls vintage vandeville, particularly in the episodes where Claude's father intervenes to prevent Claude and his amorous classmate from going all the way.

The problem with the film is that Berri's continuity is too loose to sustain undivided dramatic interest. "The first Time" seems honest enough but never incisive enough. It's an appealing ramble "The First Time" may have a special comic resonance for people who have been "Le Sex Shop." Claude's gropings and insecurities can be seen as a preamble to Berri's portrayal of the overheated and overmatched proprietor of a retail porn store. "The First Time" traces his susceptibilities back to their sources in the secret adolescent sex life of the '50s. In the long run it may be more fun on double-bills with "Le Sex Shop."