Rare film of maestro Karajan in action. MUSIC ON TELEVISION

For so prominent a figure as Herbert von Karajan, it might seem contradictory to note that he has been peculiarly camera shy throughout most of his career. For this reason alone, one must applaud Peter Gelb's enterprise in filming ``Karajan in Salzburg.'' The film, airing Friday (PBS, 9 p.m. EDT, check local listings) in the ``Great Performances'' series, is a deeply moving tribute to one of the greatest musicians of the century as he turns 80 this month.

For nearly 90 minutes, the cameras follow the legendary maestro from rehearsal room to stage, from his summer artistic home to his actual summer residence just outside his native town of Salzburg, Austria. We see him with his wife, Eliette; we see him rehearsing a production of Mozart's ``Don Giovanni''; we see him receiving a magazine award, working with young singers, and test-driving a new Porsche prototype car.

Occasionally, Mr. Karajan talks about his musical ideals. More often, we discern the depth of insight this remarkable man has to share from comments directed toward singers Kathleen Battle or Samuel Ramey during the ``Giovanni'' rehearsals or to Sumi Jo in a private coaching. At one point, he loses his patience because the opera chorus is at another rehearsal. ``If I'm in charge of a rehearsal, an agreement must be made beforehand!'' he powerfully avers.

In my favorite moment, Miss Jo, a gifted Korean soprano, lets drop that she is to sing Queen of the Night (in Mozart's ``Die Zauberfl"ote'') for recording coming up. Karajan looks aghast, finally putting a score over his head in mock disbelief. It's not that he doubts her ability to sing the role, but he recognizes the toll that particular music could take on her, vocally.

The emotional climax of the film comes with the performance of the ``Liebestod'' from Wagner's ``Tristan und Isolde,'' with Jessye Norman. She is her usual, stupendous self, but the moment is emphatically Karajan's.

As the concert begins, we flash back to Karajan and his wife in the car on the way to the hall. He says, in French, ``It's over,'' and she says ``No, nothing is over. It's the beginning.'' Then we move to Karajan's face as he stands on the podium - the face of a man utterly lost in the score and in the musical and emotional world it depicts. The camera stays close in on that face, and suddenly a fascinating documentary becomes extraordinary.