Landscapes are, above all else, a romantic endeavor of seeing the sublime in nature. Because they place little emphasis on man as a subject, landscapes were one of the last genres of art to be explored, beginning in 17th-century France with the painter Claude Lorraine and achieving a degree of refinement in 19th-century England with Constable and Gainsborough. When artists came to the New World, they immediately used landscapes to focus on the awesome grandeur of America's natural beauty.

When photography was developed in the 19th century, it was initially viewed as a vehicle for documentation, and no subject appeared before the lens more frequently than the panorama of earth and sky. An early romantic link developed between landscapes and photography, which may explain today why Ansel Adams is dead set against James Watt. The classic creators of landscape photography -- like Adams -- were present early enough to see some form of unspoiled wilderness, and the thought of this sacred land being defiled became enough to get most of them up in arms.

Thus it is that the current show, "American Photographers and the National Parks" -- at the Corcoran through Nov. 15 -- is almost subconsciously political. Pulled together by the National Park Foundation, the undercurrent of the show seems to be saying: Look at these lands; they are beautiful even when crowded with gawking visitors.

Sometimes the message comes through loud and strong, no more clearly than in Timothy O'Sullivan's "Canyon De Chelle" (1873). The early landscapers realized inherently that they were documenting the wilderness and it didn't bother O'Sullivan that the tents of his expedition party were visible in the foreground of his image, dwarfed by the imposing majesty of the canyon rocks. He knew that the human rudiments stuck in his frame paled in comparison to the scene he was capturing.

As did many of the other classic photographers. Eadweard Muybridge, better known for his locomotion studies, places a lone figure in his foreground on Glacier Rock to give some sense of size to Yosemite Falls. George Fisk has two women "Dancing on the Overhanging Rock" at Glacier Point in the same park, perhaps to jest at the folly of human endeavors when confronted with such grandiose symmetry. Imogen Cunningham sets sprites loose in Mount Rainier National Park, to hint at some marriage between between human and natural forms. William Henry Jackson places figures beside Old Faithful to give some measure of the height of its plume.

The natural splendor goes on and on and on, often without human intrusion. Ansel Adams and Edward Weston, Carlton Watkins and Minor White, William Garnett and Laura Gilpin all have unique views of of the earth.

One might wish it ended here, but curator Robert Glenn Ketchum has also included a number of contemporary approaches to landscape photography that stretch the definition a bit far. Admittedly all the images here were made in national parks (Jerry Uelsman's composites have external additions), but what Richard Misrach's strobed shot of a seemingly dead cactus tells about natural parks is difficult to decipher. It seems more a part of the moon.

It's this part of the show that's troubling. There's been an auto-despotic trend among contemporary photographers to make pictures of other people making pictures, a dead-ended, incestuous process that's as repetitous as rock 'n' roll songs about life on the road or films about people making movies. What once was an eye-opening, horizon-widening genre has become a drearily introspective attempt at commentary on the photographic process itself.

There are plenty of these dreary, tired images here. One suspects the world would be no emptier a place without David Mussina's and Roger Minick's snaps of tourists. Even Lee Friedlander seems out of place with tourists snapping away at Mount Rushmore, the familiar stone figures reflected in windows behind them. Friedlander's normally appealing sense of ordinariness is too out of place when surrounded by mighty peaks well recorded long ago. Some of this new imagery could be used to support the arguments of Mr. Watt.

This is not to say that contemporary photographers are incapable of squaring off with natural beauty: One need only glimpse William Clift's detailed sense of spaciousness and Joel Meyerowitz's awesomely subtle control of color.

A final note on hubris: It seems odd that curator Ketchum would include here one of his own photographs in a format bigger than all but one or two of the other 170 images in the show. There are some perks due any boss, but this is carrying authority a bit far.