Wagstaff: Before and After Mapplethorpe by Philip Gefter, book review

Exploring a felicitous meeting between visionary collector and erotic photographer

Wagstaff's greatest project: Robert Mapplethorpe, November 1983 (Rex Features)

Sam Wagstaff knew there was something special about Robert Mapplethorpe the moment he set eyes on him. "Who is that?" he asked, pointing to a small photo-booth picture lying on a friend's table. "I want to meet him." It was 1972 and Wagstaff, a handsome 50-year-old curator, had recently given up his job in Detroit and moved to New York to begin life afresh.

The image of the sexy young man in a sailor's cap – Mapplethorpe was a struggling 25-year-old artist at the time – appealed to Sam's sensibility, and he became even more intrigued when his friend told him that Robert liked to photograph himself naked. "Is this the shy pornographer?" asked Wagstaff, when Mapplethorpe picked up the phone. The two men became lovers on the day they met, and, according to this terrific biography, the history of photography was changed forever.

Today Wagstaff is remembered as a connoisseur of photography – he sold his collection to the Getty Museum in 1984 for $5m – and as one of the key people responsible for elevating the medium to the status of fine art. Back in 1972 few institutions collected photos and the market for both vintage and modern prints was in its infancy.

In his meticulously researched account of Wagstaff's life, Philip Gefter sets out to discover what made Sam such a visionary collector, and to show that without each other he and Mapplethorpe might never have made their unique contributions to art history.

Wagstaff was born in New York in 1921 to a wealthy patrician family. When he was 10 his parents divorced and his glamorous mother – Olga – remarried, taking Sam with her to live on Majorca. Sam adored his mother, but Olga was a remote figure who later left him at boarding school when she returned to New York. Gefter considers that these circumstances had a profound effect on Wagstaff's development, leaving the boy with an emotional vacuum. His nascent homosexuality only added to his sense of alienation. He began to collect beautiful things to fill the void: first cacti, later paintings, photographs and pretty young men.

After graduating from Yale, Wagstaff worked in advertising before returning to university to study art history. An inheritance from his stepfather allowed him to give up his job and become a full-time collector. He had a discerning eye and quickly acquired important paintings by Pollock, Warhol and others. But with Mapplethorpe's encouragement he turned his attention to the neglected field of photography and the pair went on a 10-year spending spree, snapping up everything from the earliest Fox Talbots to some of the most iconic works of the 20th-century.

But Mapplethorpe was Wagstaff's greatest project. Sam bought his boyfriend a loft and used his influence to promote his work. Mapplethorpe, meanwhile, learnt his craft from the masterpieces in Sam's collection and his erotic photographs of naked men and flowers soon made him famous – and notorious – across the world.

Although they were no longer lovers when Wagstaff died from Aids in 1987, Sam left Mapplethorpe the bulk of his estate, a vast legacy which then passed to the Mapplethorpe Foundation when Robert himself died from the virus in 1989, aged 42.

Gefter is very good on New York's gay milieu and his book is full of racy details. We learn how Wagstaff grew sprouts in his cupboards, used cocaine to heighten his pleasure when examining potential purchases, and how, during his final illness, he took a piece of antique silver to bed with him. At the end it was no longer a beautiful body he wanted by his side, but the kind of exquisite object that had been his lifelong solace.