Alfred Stieglitz (1864-1946) was one of America's foremost champions of modernism. He was the first to show American viewers, in his small pioneering gallery in New York known simply as ''291,'' art by Matisse (1908), Rousseau and Cezanne (1910), and Picasso (1911). And over the next three years the works of Brancusi, Picabia, and Braque were exhibited there as well.
He also helped launch the careers of American painters, most particularly those of Marin, Hartley, Dove, Weber, and O'Keeffe. And he was intimately involved with several of the most vital literary figures of the time.
But it was photography that claimed his deepest attention and that was responsible for his greatest fame. His all-consuming passion led him to become not only one of the best photographers the world has seen, but one of photography's deepest and clearest theorists as well.
The most comprehensive exhibition ever mounted of Stieglitz's work is on view at the Metropolitan Museum here. It consists of 171 photographs drawn from the collections of the National Gallery of Art in Washington, including many works never exhibited before. It traces the development of his technique and style from the mid-1890s through 1935 and includes early European studies, portraits of artists and writers (including several of Georgia O'Keeffe), and studies of clouds, New York City, and Lake George, N.Y.
Even hard-line reactionaries who insist that photography is not an art form must be impressed by Stieglitz's accomplishments. Such works as ''Winter, Fifth Avenue,'' ''Spring Showers,'' ''The Steerage,'' ''Waldo Frank,'' and most particularly his ''composite portrait'' of Georgia O'Keeffe (over 300 photographs taken of her between 1917 and 1937) are superb. And such studies as ''First Snow and the Little House'' and ''Spiritual America'' are among the most clearly perceived and sensitively executed photographic images anyone has produced.
It's a beautiful show. After its Aug. 14 closing at the Metropolitan, it travels to the Art Institute of Chicago, where it will be open to the public from Oct. 18 through Jan. 3, 1984.
I also recommend the exhibition catalog. ''Alfred Stieglitz: Photographs and Writings,'' by Sarah Greenough and Juan Hamilton, was published by the National Gallery of Art and Callaway Editions. It has 246 pages and 73 superb reproductions of Stieglitz's photographs, and sells for $75 (cloth) and $39.50 (paperback). A 'performing' painter
Some artists paint as though they were musicians with a full orchestra at their command; others as though they were performing on a violin with only one string. Then there are those who paint as though they had never progressed beyond their first rehearsal.
Robert Zakanitch is a ''performing'' painter with two ''strings'' at best, who nevertheless manages to create some extremely handsome and interesting art. He does have detractors, some of whom claim his work is merely decorative and others who insist it's a bit too precious. Yet I've discovered that his canvases often stand out quite dramatically in the midst of others considered more ''serious'' and ''important.''
His images do tend to be flat and his colors extremely subtle and ''refined.'' But precisely the same thing can be said of much of the best art of the past 80 years.
Many cannot forgive him, it seems to me, for the fact that his is largely an art of sensibility rather than of theory or ''expression'' - and that it exists very much on its own with a minimum of historical precedent and justification. That worries us, but the fact remains that he is a very good painter - and we should be able to accept him as that.
I was particularly aware of that while studying several of his nearly abstract paintings in the group show at the Robert Miller Gallery here. They were simpler and far less exotic than those by Louisa Chase or Roberto Juarez, also on view, but they were also superior.
It's not that Chase and Juarez aren't interesting, even good painters at times. They are. It's just that Zakanitch has a broader and clearer perspective on art than they seem to have and is capable of focusing all he has toward its creation. His work, as a result, while somewhat tenuous and fragile, speaks clearly and truly and has an identity as art considerably beyond that of many of his more complex and solemn contemporaries.
At the Robert Miller Gallery, 724 Fifth Avenue, through July 30.