S.J. Freedberg, a specialist in the painting of the High Renaissance, has been named the new chief curator of the National Gallery of Art. When he takes the post Sept. 1, he will immediately become the best-known art historian on the Gallery's large staff.

In his field, Freedberg is a legendary figure. His intimidating scholarship, acute connoisseurship, cultivated wit and occasional eccentricities have made him one of the most feared and yet admired members of the faculty at Harvard, where he has taught for 30 years.

Philippe De Montebello, director of the Metropolitan Museum of Art, is a former Freedberg student. So are Everett Fahy, director of New York's Frick Collection, Earl A. (Rusty) Powell III, director of the Los Angeles County Museum of Art, and Freedberg's boss-to-be, the Gallery's J. Carter Brown.

"There is almost nobody in the trade I haven't taught," said Freedberg.

The Gallery once was respected for the art in its collections rather than for the scholars on its staff. That situation has changed. Freedberg's appointment--and those of John Wilmerding, who became deputy director Feb. 1, and Henry Millen, who heads the Gallery's Center for Advanced Study in the Visual Arts--demonstrates, in Wilmerding's phrase, that "Carter Brown wants senior scholars, rather than art bureaucrats, to run this institution."

Brown, at Harvard, studied 17th-century Dutch painting. Wilmerding is an Americanist. Freedberg's field is the Italian art of the High Renaissance and Mannerist periods. As chief curator, he will be consulted on acquisitions. He also will supervise the conservation laboratory and those curatorial departments concerned with European art.

Sydney Joseph Freedberg, 62, was born poor in Boston, though one would never guess that from the way he speaks. He has a partly English, partly Boston Brahmin accent that he has called "pure affectation." He made it up himself. Abigail Gerdts, who studied with Freedberg at Harvard's Fogg Art Museum, remembers him as "the glamorous and fearsome star of the department. He lectured in glorious, rolling prose. Heads turned when he walked down corridors. He was famous with undergraduates for eating them alive. Yet he also was a wonderfully patient teacher. He'd spend hours with the dumbest students."

Brown calls him "coruscating." Wilmerding, who also studied at Harvard, says "I was terrified of Freedberg."

Freedberg, a friend and student of the late Bernard Berenson, said yesterday, "It would not be inaccurate to describe me as perpetuator of his methodologies." Freedberg belongs to a scholarly tradition, established by Charles Eliot Norton, Berenson, Paul J. Sachs, the Mongan sisters and other Harvard art historians, that stresses meticulous connoisseurship rather than art theory. "The work of art is primary," said Freedberg. "Unless you start with the evidence of the object, you are up a tree."

His appointment to the Gallery seems a sort of homecoming. Many of its patrons--founder Andrew W. Mellon, the Wideners, the Kresses--and its directors, too--John Walker, Carter Brown--were taught to view Italian art in the Berensonian way. In the museum's early years, while Walker was chief curator, he seemed to think that questioning the attributions of his old Italian paintings was in some way impolitic. But their givers now are dead. "I should like to see the Gallery accelerate the adjustment of attributions where these seem to be necessary," says Freedberg.

"I also shall encourage in every way an intimate collaboration between conservators and curators," he added. "I hope the curators will haunt the laboratories."

The Mannerist painting that Freedberg loves is poorly represented in the Gallery's collection. So is 17th-century Italian art of the sort now on display in the Naples exhibition. "The representation of pictures of that period is less than ideal," said Freedberg. "We shall try to build in those areas where the Gallery's collecting has stopped short."

Freedberg partially replaces Charles Parkhurst, who retired as assistant director/chief curator Feb 1. But Parkhurst spent most of his time on Gallery administration. Freedberg won't.

Freedberg, who holds three Harvard degrees and has chaired the art department there, was asked why he's leaving teaching after lo, these many years. "Lo, these many years is part of the answer," he responded. "I would have retired in June at any case. My time of Harvard service has come to a natural end. I'm delighted to have the opportunity of working at full speed in Washington, instead of winding down."

His publications include "Painting in Italy 1500-1600," "Painting of the High Renaissance in Rome and Florence," "Connoisseurship, Criticism and Art History in the 19th Century" (a 20-volume series, of which he was the editor), and monographs on Parmigianino and Andrea del Sarto. His museum experience, in addition to his service as acting director of the Fogg, includes working as an adviser to the Metropolitan and the Boston Museum of Fine Arts.