Whether or not you like the Hayward Gallery's exhibition "Ansel Adams at 100" probably depends on your attitude to mountains. If the mere sight of a craggy peak has you adopting a reverential pose, then pack your crampons and make your way up the concrete escarpment that is our own very little bit of brutalism on the South Bank. If you know anyone with a beard who spends their time bagging Munros, then buy them a season ticket.
For the rest of us, however, the exhibition suffers from the law of diminishing returns. By the time you reach an image as sensational as El Capitan rearing out of the mist in Yosemite National Park, you will probably have seen quite enough rock faces, scree and precariously clinging plant life to last you for an afternoon.
For Adams, the wilderness was essentially a sacred site, as it was for the Greeks who placed Zeus on top of Olympus, the Japanese who built a Shinto shrine on Fujiyama, and the Scots who insisted Muriel Gray be sent up Ben Nevis, in the vain hope she might get lost. He believed geology could offer "a transcendental emotional and spiritual experience". But again, there's a limit to how many religious icons anyone can take at one time.
Perhaps I'm prejudiced. Halfway through the exhibition, I was transported back to an especially deadly primary school class, where a fervent Scottish nationalist attempted to drum into our young heads all the names of the Trossachs. How else could we be truly Scottish if we didn't know our own landscape? There's something of the narrow nationalist in Adams, who was determined to make the wilderness part of the rhetoric of American exceptionalism, just as Western movie-makers had done.
No wonder his work appealed so readily to his conservative environmental friends in the Sierra Club, with their paranoia about the contagion of international Bolshevism.
A concerted effort has been made over the years to recreate Adams into a less narrowly American figure, less narrowly nationalistic. From this angle, his environmentalism is of global significance, and his photographs are close to propaganda for the rights of Planet Earth: Rachel Carson on silver nitrate. This sainthood continues with this exhibition in which the organiser John Szarkowski tries to present him as a model of the progressive, committed artist.
Unfortunately, the reality is much more ambivalent. Adams spent most of his time working as a commercial photographer, putting his powerful images to work for advertising agencies. One important client was Standard Oil, which sold his images as part of a collection to remind tourists of "scenic highlights to visit on your next trip". There is nothing necessarily wrong with that, but it does sit uncomfortably with Adams's stated opposition to road building within the national parks and to his earnest self-image, which was promoted most notably in his San Francisco retrospective in 1963, "The Eloquent Light". Somehow it slipped the notice of this exhibition as well.
The catalogue claims that Adams presented the world to us as a "deep moral cryptogram". Adams himself argued that "there is just as much social significance in a rock . . . [as] in a line of unemployed".
This wasn't a view shared by other equally talented photographers. For many, landscape felt irrelevant during the Depression and the Second World War, as they put themselves at the service of high political ideals. Cartier-Bresson reputedly remarked: "Now, in this moment, in this crisis - with the world maybe going to pieces -to photograph a landscape!"
Edward Weston, Willard Van Dyke and Dorothea Lange identified the commercial instinct as the biggest threat of all to the wilderness, and took Adams to task for what they thought was selling out.
In the end, the exhibition's attempt to portray Adams as some sort of deep green American saint does him no favours. For one thing, it means the full range of his work is not represented. Instead, we see one snow-swept moral cryptogram after another.
Szarkowksi shows us none of Adams's best portraits, such as his astonishing photographs of the Japanese Americans who were interned in Manzanar Relocation Center, which demonstrate that Adams could be explicit and socially conscious when he chose to be.
Perhaps that would have been too controversial. After all, the exhibition is sponsored by Hewlett Packard whose chief executive is pleased to announce that "the values embodied by Ansel Adams are shared by HP". That'll be a reference to all those wonderful piles of toxic computer parts slowly building up across America -Yosemite-sized mountains in fact.
"Ansel Adams at 100" is at the Hayward Gallery (020 7921 0600), South Bank, London SE1, until 22 September