First you spot languorous Marlene Dietrich. Then pretty Robert Taylor, a severe Bette Davis, an innocent Clark Gable. Joan Crawford smothered in fur. A sad Garbo, a sexy Rita Hayworth, Cary Grant in his 20s and Louise Brooks in miles of pearls.

"Hollywood Portrait Photographers, 1925-1945," is the National Portrait Gallery's tribute to 24 studio photographers whose star-making machinery created these icons. What once was dished as PR from MGM and Warner is now art. Mainly, though, the exhibit is a chance to gawk again and again at everyone's favorites.

"I never paid much attention to the glamour bit," Ann Sheridan said. "Dietrich is glamour! The queen. Like Crawford. Like Garbo was, still is . . . None of us girls -- Lana, Rita, Dorothy Lamour -- we couldn't possibly touch it. Those are sweaters you're talking about, darling, that's not glamour."

Still, each star cast a spell, defining glamour through the silver screen. Katharine Hepburn called the camera a flatterer. She let herself go in front of the lens, she said -- "I mean, you can't photograph a dead cat. You have to offer something."

As usual, the celebs being honored here -- Ted Allan, George Hurrell, Ernest Bachrach and the other studio photographers -- will be lost in the glitter. HOLLYWOOD PORTRAIT PHOTOGRAPHERS -- At the National Portrait Gallery through March 20. ON THE SCREEN -- A series of film classics are scheduled in conjunction with the exhibit. This weekend, WATERLOO BRIDGE (1940) with Vivien Leigh and Robert Taylor, Friday at 7; BRINGING UP BABY (1938) with Katharine Hepburn and Cary Grant at 8:45. Repeated Saturday at 1:30 and 3:15.