When you look at a portrait of a celebrity by photographer Annie Leibovitz, you also receive a clear message about the status of Leibovitz herself. The time and care evident in each picture shouts out that she has unrivalled access, and it’s true. While most journalists and photographers would scrape the ground till their knees are raw for five minutes of a star’s schedule, Leibovitz is granted as long as she needs to produce images that are often complex. Demi Moore, for example, remained still for 12 hours while a suit was painted on her body for a Vanity Fair cover shoot.

We, too, feel indulged by the stars that indulge Leibovitz when we look at such photos. We also enjoy the fact that, in this particular relationship between documenter and star, the boot is ostensibly on the other foot – Leibovitz has the power.

Annie Leibovitz was born in Connecticut in 1949. Her father was an air force officer and her mother a modern dance instructor. She got her break in 1970 when she sold a picture of Allen Ginsberg smoking marijuana on a peace march to Rolling Stone magazine for $25. Three years later she became the magazine’s chief photographer. During 1975, Leibovitz was famously embedded with the Rolling Stones on their American campaign of rock’n’roll naughtiness. She came away with the scar to prove it – a cocaine habit that took five years to shake. ‘I went on that tour to get to the heart of something,’ she said later. ‘I was very reluctant to throw myself into something that deep for some time afterwards.’

Originally Leibovitz saw herself as a photojournalist, but she developed into a portraitist through shooting covers for Rolling Stone. She moved away from pure documentation and evolved a high-concept form of composition in which her subjects are shot in carefully contrived poses. It remains her trademark still today. In 1980 she produced one of her most memorable pictures in the style, an iconic Rolling Stone cover shot of Yoko Ono and John Lennon in which a naked Lennon clings to Ono like the young of some marsupial to its mother, holding her close to him and kissing her on the cheek. Above her, Ono’s long black hair spread outs, romantically, like a headdress. Taken just before Lennon was murdered, the photo communicates the profound bond between the couple better than words.

The Eighties were a different era and Leibovitz moved to a different magazine with a different ethos. At Vanity Fair, which she joined in 1983, she has continued to produce high-concept compositions – Whoopi Goldberg photographed in a bathtub of milk, the cast of The Sopranos recreating The Last Supper – along with more conventional portraits.

At their best, her set-ups capture an essential truth about the sitter, as with a 1988 portrait of Arnold Schwarzenegger that brilliantly expresses his virile, aristocratic aura. Shot in profile, Arnie sits atop a noble-looking horse, wearing white breeches and riding boots. The pose looks like one a 19th Century sculptor would contrive for a town square statue of a military hero, except Arnie has a stubby cigar in his mouth and isn’t wearing a shirt, which puts a grin on the face of the image.

Leibovitz’s prodigious work for Vanity Fair has defined the lavish style and flavour of the magazine for the last 20 years. During her editorship, Tina Brown once said: ‘She makes the pages sing’. Graydon Carter, the current editor of Vanity Fair, praises her for her unrelenting perfectionism: ‘She will spend two days shooting somebody. She will wear the subject down to a point where their defences are down. She gets the one image that goes further in.’

In the process of becoming the portraitist of choice for the rich and famous, Leibovitz has become just as much a celebrity – in some cases even more so – than her subjects. A Leibovitz picture, such as her much-discussed cover shot of a seven-month pregnant Demi Moore, can be a media event in itself.

Leibovitz and her retinue work out of a converted garage on Manhattan’s West Side. Her shoots may involve as many as 30 assistants who, one insider has reported, appear to undergo a collective nervous breakdown before a big assignment. She lives in the same apartment block in the West Village as her long-term companion, the intellectual Susan Sontag, whom she first met while taking her portrait in 1990. Two years ago, Leibovitz surprised everyone, herself included, when she gave birth to a daughter, Sarah Cameron, at the age of 52. ‘It was the 99th hour,’ she has said. ‘It is just amazing. Definitely the cliches are all true. I was almost resigned that it wasn’t going to happen.’

Leibovitz’s most recent book, American Music, saw a return to photographing musicians – and a return to a rawer, gutsier style of portrait. Whatever she does, wherever she wanders creatively, her place in the pantheon of great photographers is assured.