Rick Norsigian holds up a photograph made from a glass negative purportedly shot by the late Ansel Adams during a news conference in Beverly Hills in July. (Nick Ut/Associated Press)The Ansel Adams Publishing Trust, which guards the legacy of the famed U.S. photographer, is suing a man who is selling prints from negatives purported to be by Adams.

The trust filed a lawsuit in U.S. federal district court in San Francisco on Monday, seeking to stop Rick Norsigian and PRS Media Partners from selling prints and posters using Adams's name, likeness and trademark.

In July, Norsigian told a press conference that a trove of old glass negatives he had stumbled upon a decade ago had recently been authenticated by a team of experts as Adams's work.

According to Norsigian and his lawyer, Arnold Peter, the team had concluded that the negatives were early works by the nature photographer that were believed destroyed in a fire in 1937.

Norsigian set up a website to sell prints and posters created from the glass negatives, and has planned an upcoming exhibition at a Beverly Hills gallery.

'Protect his work and reputation'

However, the trust has been skeptical of the find from the start, and called Norsigian's actions a fraud and a scam.

"I'm sure Ansel never would've imagined a scam on this scale," said Bill Turnage, the trust's managing director.

"I never thought it would come to this, but we have to try to do our duty to protect his work and reputation."

The trust and members of Adams's family have noted that many photographers also took pictures of the same places Adams had during the same time period. For instance, the niece of an Adams contemporary, photographer Earl Brooks, has come forward saying one of her uncle's photos looks identical to one of Norsigian's negatives.

The lawsuit accuses Norsigian and PRS Media Partners of trademark infringement, false advertising and other claims. It does not specify damages. However, the trust has asked the court to order the defendants to turn over the profits from any sales.

Adams, who died in 1984 at age 82, started his namesake trust in 1976 to protect his work and artistic legacy.

His moody black-and-white prints are highly coveted by collectors, with his image, Clearing Winter Storm, Yosemite National Park fetching a record $722,500 US at auction in New York in June.

With files from The Associated Press