She is the world's most famous celebrity photographer, whose portfolio contains some of the most iconic images of the past 30 years, not least the glamorous pictures of Michelle Obama on the latest cover of Vogue. As such Annie Leibovitz is hardly the kind of person you would normally associate with going to a pawn-broker.

But it seems that in these unusual times even the likes of Leibovitz need to find cash in unusual places.

The photographer has turned to a company called Art Capital that specialises in lending money with fine art as the collateral. The New York Times disclosed yesterday that Leibovitz has borrowed about $15m (£10m) from the firm in two tranches.

Records show she secured the loan partly against property, but also by putting up as collateral the copyright, negatives and contract rights to every photograph she has ever taken or will take in future until the loans are paid off.

Such an exceptional step, involving in essence the pawning of her entire life's work, may in Leibovitz's case be explained by the tumultuous few years she has been through. Her long-time friend Susan Sontag died in 2004, and she has been in costly litigation over the renovation of some of her properties.

But Leibovitz is part of a wider trend that Art Capital and other specialist lending institutions like it say has intensified since the start of the global economic crisis last autumn. Wealthy individuals and institutions have increasingly turned to the firm for help – numbers have risen by 30% to 40% since before the crash.

"What's amazing is that individuals and institutions who previously we thought were untouchable are being deeply affected. People who were truly enormous financially are now scrambling," said Ian Peck, joint owner of Art Capital.

The numbers tell the story. Art Capital expects to make about $120m in loans against art this year, up from about $80m in 2008. Some of that has gone out to several hedge-fund managers, hit by the Wall Street collapse, who have put up striking contemporary and modern art works.

The company's offices, which are located next door to the designer Vera Wang's wedding dress showroom in Madison Avenue, resemble one of New York's more select art galleries, which to some extent is what it is.

Currently on display are a set of black and white photographs from the 1930s and 40s by the Magnum photographer Ernst Haas, as well as a room full of Old Masters including 17th century works by the French painter Simon Vouet and Francisco de Zurbarán from Spain.

Among the art works that have recently been taken in by the company, and put into secure and climate controlled specialist art warehouses for safekeeping, are pieces by Willem de Kooning, Mark Rothko, Andy Warhol, Henry Moore and even Picasso. Cash-strapped clients have borrowed money against vintage film posters, antique teddy bears and valuable scientific instruments.

Peck has also witnessed casualties of the recent spate of Ponzi schemes – fraudulent pyramid scams – come pleading for help with art collections as collateral. But in these most desperate of cases, he said, the company would rarely become involved. "If someone is at death's door financially, we can't help them. Several times a month we see refugees from Ponzi schemes; their stocks are gone, the money's gone and they are looking at their hard assets."

The spike in business to financial firms that lend against art is being reported across the US. Other prominent artists have also become involved in using their own work to generate funds, including the film director Julian Schnabel.

ArtLoan, a company specialising in this work in San Francisco, told the New York Times its growth in the last year had been "exponential".

Another New York outlet, Fine Art Finance, deals with clients who can put up art and antiques valued at a minimum of $2m. It lends up to $100m for up to 20 years.

Firms like ArtLoan and Art Capital typically lend out 40% of the value of the art works they take in, making most of their profit by charging interest of 6% to 18%.

Peck said only about one in 10 of the deals end in default. "Our aim is to avoid defaulting at all costs. Given the trouble involved in a default, it's better karma and business not to."

Even if the works are not sold, and remain in the client's ownership awaiting their return in better economic times, Peck admits that this is intensely emotive stuff. "It's akin to giving up your home, particularly for people who have built up collections over many years. People don't feel emotionally about stocks and bonds, but they certainly do over art."

In the case of Leibovitz, Peck insists that very few places could have coped with her request for money based on her images. "We're pleased to have her as a client and it's a very good fit. We are one of the few – if not the only – lender who could have valued her body of work; that's a fairly esoteric thing to value."

• This article was amended on Saturday 28 February 2009. Michelle Obama's picture is on the cover of the March issue of US Vogue, not Vanity Fair. This has been corrected.