Clarence Lippard, drifter, Interstate 80, Sparks, Nevada is a portrait which also has many of the qualities of a landscape photograph. Seen in void white space, Mr Lippard amounts to foreign territory. His face is a parched wasteland, an expanse of cracked mudflats and fields of scorched stubble. His hair is dry and combustible. His hand is a freckled stone. His alienness is both his weakness and his strength, and he is aware of the fact. He is poor and his clothes are cheap and he does not have a settled place in the world but he is still extraordinary and still his own man. He stares down his photographer with a defiance bordering on contempt. You can get my picture, Mr Avedon, but you can't get me.
The Avedon retrospective which opened last week at the National Portrait Gallery has been called Evidence, but Richard Avedon, Drifter might have fitted better. The career that it memorialises comes across as a meander at the end of which a destination is eventually reached and something truly remarkable is done.
"The best portraits," Avedon once said, "are always emperors or postmen. People who are all self-image, or people who have no self-image at all. They come with a kind of dignity to the camera." Avedon himself has divided his life unevenly between the self-possessed and the dispossessed, spending the majority of his time photographing the rich and the brilliant and the notorious.
The NPG has emptied its new 20th-century galleries to accommodate the exhibition so it is clearly important that Avedon should be seen to be a master of the photographic image. The catalogue to the NPG's exhibition reprints a stained note once sent to the photographer by the poet Marianne Moore, in which she remarks of the pictures he has just taken of her that "You certainly have the art of it!", before going on to request numerous detailed changes to her image. The letter is meant to substantiate the hagiography of Avedon to which it is an illustration, but it has the opposite effect. Moore's automatic assumption of Avedon's pliancy is rather shocking.
It also goes to the heart of his character as a magazine photographer. The Avedon of Vogue and Harper's Bazaar is a gigolo. Avedon has always had the knack of turning the emperors and empresses whom he has photographed into attractive but distant performers of public roles.
Access has been granted to him without qualms, in the knowledge that there is no fear of disclosure - no chance of him seeing or eliciting anything strange or haunting or unpredictable enough in his sitter to touch any of the selves behind the mask. He has photographed Marilyn Monroe, who looked bored when he did it, and Audrey Hepburn, who looked pretty (but then she always did). He has photographed Humphrey Bogart and Rudolf Nureyev and Charlie Chaplin and Pablo Picasso - but in no single one of many such cases has his image become the image of that person, the picture that has defined and fixed them in the public mind's eye.
It is not, unhappily, that Avedon has gained something profound in exchange. This has been plain since 1958 and the publication of his first book of portraits, Observations, which is an especially pompous title considering how unobservant nearly every photograph in it is. Intimacy has been sacrificed for nothing more than slickness. The famous people whom the photographer has pictured never seem to have allowed him much more than the slightest, temporary familiarity. On occasion he has compensated for the lack of feeling in his pictures in ways that suggest he is conscious of it as a failing. His Humphrey Bogart, for instance, is seen in extreme close- up, but the result is only a faked intimacy since the actor presented to Avedon such an urbane, uninterested mask of affability. It is rather like being blanked (in the nicest possible way) by someone dauntingly celebrated.
Not many of Avedon's fashion photographs have been included in this show. Perhaps fashion photography is not considered a serious occupation by the exhibition organisers. Perhaps Avedon himself would prefer to forget that he has spent much of his professional life working to commission, willingly producing pleasing pictures of pretty girls in pretty frocks. Whoever's intentional amnesia lies behind the omission, it is a miscalculation.
Avedon's willingness to please and his extreme reluctance to confront or unmask or otherwise challenge those who have ended up in front of his lens cannot be covered up - and to help people realise their most glamorous fantasies of themselves is, in any case, one of the highest vocations of the portraitist. The grimly puritan view that Rembrandt was a necessarily more profound painter than Rubens, the notion that those who depict people as they are must be more worthy than those who depict people as they would like to be - these are widely held preconceptions that deserve to be tested and challenged. The problem for Avedon has been that, having set out to please vanity, he has not pleased it inventively enough.
Artists are generally vain yet they are, revealingly, the people whom Avedon has had the very greatest difficulty in depicting. His photographs of men whom he considers brilliant are particularly and embarrassingly unsuccessful. Overawed by Picasso, quite unable to recognise that the man's talents were inextricable from his rowdy, nervous humanity, Avedon turned him into a romantic clich: an entranced seer, gazing heavenwards for inspiration. The old goat looks as though he found the whole act of imposture tedious in the extreme.
Picasso's boredom bears ample witness to the fact that Avedon's shortcoming as a photographer has not been the fact that he is a brown-noser, but the fact that he is an insufficiently imaginative one. Annie Leibowitz is a far more considerable, witty, brilliant and amusing reinventor of the glamorous selves of glamorous people than Avedon has ever been - although for some reason it seems to be heresy, at least in America, where Avedon is taken very seriously indeed, to say so.
Avedon has been nothing if not various. From the start of his career, he has photographed the poor as well as the rich, down-and-outs as well as up-and-ins. He has not often done it especially memorably, and perhaps admitted (rather touchingly) his sense of his own failings when he said of a fellow photographer: "We walk around with Cartier-Bressons in our heads, thinking they're our history. Our memories of what we never witnessed were created by him."
The same cannot be said of Avedon, although he has regularly aspired to match those triumphs of universal witnessing. His solutions to the momentous events of modern history have tended almost invariably to be banal. When Kennedy was shot, he went to Times Square and photographed various appropriately saddened individuals holding the same newspaper, with its banner headline "PRESIDENT SHOT DEAD" held up to the camera. Only someone with a wide streak of vulgarity could have strained for profundity like that.
Avedon has also tried his hand at social conscience, although his artfully grainy pictures of lunatic asylum inmates and his emphatically brusque and horrible images of Vietnamese napalm victims also manage to strike subtly false notes - in one case it is as if he cannot really bear to sympathise with his subjects and so has turned them into abstractions of mental disturbance; in the other it is as if the blatancy of such harsh witnessing is all he can come up with to salve his (and America's) guilt. The suspicion lurks, however, that the photographer has put on what he thinks are the appropriate feelings: they are the emotional equivalent of paste jewellery. When he has striven for the Decisive Moment, (as in his cub journalist shots of the fall of the Berlin Wall), the results have been little short of disastrous.
None of this is to say that Avedon's has not, in the end, been a fruitful career. He has made some great photographs (and that is enough to be grateful for) and they were created by the last of his many alter egos, Avedon the clear-eyed realist - although the divide between the several different sides of his character as a photographer may not be as wide as some puzzled commentators appear to find it.
With the series of pictures that he called In the American West, Avedon created an extraordinary and compelling body of photographic images. The effortless superiority of these pictures to everything else in the NPG retrospective is stark and startling. Suddenly, you find yourself in the presence not of images but of people themselves - touched and disturbed by a reality that is, literally, staring you right in the face. Too ground down and hungry and indifferent to cut themselves off from Avedon's inquiring camera, the people he photographed in Nevada and Utah and Colorado and New Mexico simply stood there and allowed themselves to be recorded for posterity.
The effectiveness of these pictures has something to do with Avedon's subjects and their lack of barriers. But it must also have much to do with the photographer's late recognition of his own limitations. Knowing, in the end, that it was his eternal fate to be superficial, unchallenging, unimaginative, emotionally cold and banal, Avedon brilliantly evolved a form of photography in which none of those defects can spoil or diminish. Having done that, he got to work. These people led hard lives, were marked by them - and then Avedon took their photographs. To look at them in their grim and self-contained otherness feels like witnessing actual slices of human existence itself: all these people have is their sense of themselves, and they cling to it, each of them, as fiercely and defiantly as life itself. Avedon had enough sense, in his best work, to leave himself out of the picture.
n At the National Portrait Gallery, London (0171-306 0055), to 11 June