Bought at a garage sale for $45, the photographs worth more than $200m

Rick Norsigian, a Californian antique buff, knew exactly what he was looking for when he went rooting through a Fresno garage in 2000. He was looking for a vintage barber's chair, to add to his eclectic collection of old telephone switchboards, petrol pumps and aeroplane propellers. But when the chair turned out to be a dud, he chanced upon something that changed his life: two boxes of antique glass negatives which, a Beverly Hills art appraiser declared yesterday, were the work of Ansel Adams, the father of American photography.

Mr Norsigian, a construction worker and painter, had bargained his garage sale counterparty from $75 down to $45 for the lot. Now it seems the collection is worth at least $200m (£129m). "When I heard that [figure], I got a little weak," he said.

Unveiling the photographs at a Beverly Hills gallery yesterday, after years of scepticism from the art world, an attorney, Arnold Peter, said a team of experts had finally concluded the 65 negatives were the early work of Adams, most likely taken between 1919 and the early 1930s and rescued from a fire in 1937. The photographer declared himself heartbroken at the fire, which destroyed an estimated one-third of his work.

Adams's black and white pictures of the rugged beauty of the American West are now a staple of US greetings cards and posters. His work not only helped establish photography as an art equivalent to painting or music, but also stoked the nascent national parks movement in the US. A retrospective at the Museum of Modern Art in New York in 2003 to celebrate what would have been his 100th birthday the previous year declared him "one of the great photographers of the 20th century and also one of the best-loved spokesmen for the obligations we owe to the natural world".

When Mr Norsigian and his friends noted the similarities between his negatives and Adams's famed photographs of Yosemite National Park, he decided to hire Mr Peter to investigate further, and the pair declared the results of that investigation yesterday. "You look at these photographs and they take your breath away," Mr Norsigian declared. "But it is even more meaningful and rewarding to finally have the leading experts confirm what I believed in my heart when I saw the images for the first time."

Handwriting experts confirmed that writing on the envelopes in which the negatives were found belonged to Adams's wife, Virginia, Mr Peter said. A meteorological expert compared one of Adams's most famous photographs with one found in the negatives and by looking at the cloud formation, the snow on the mountains and the shadow cast by a tree, determined that the two photographs were taken on the same day at approximately the same time.

"There is no definitive authority charged with authenticating photographs," Mr Peter said. "And unlike a painting there is no signature linking the work to the artist. So, we decided to apply the highest possible evidentiary standard we could think of. Every individual who has actually examined all the evidence we have gathered has come to the same conclusion – these are, in fact, the works of Ansel Adams.

"These photographs are really the missing link. They really fill the void in Ansel Adams' early career."