Instantaneously visible photographs are nothing extraordinary to today’s maven and amateur shutterbugs who document the world with digital cameras.

But not so long ago, Polaroid was the only way to both take pictures and evaluate them within a matter of minutes.

The clever test that Edwin Land devised in 1947 ” when he introduced the first instant photographic process ” to measure the quality of Polaroid products has generated a massive art collection chock full of notable names: Ansel Adams, Minor White, Andy Warhol, Judy Dater, William Wegman.

Land hired them to test Polaroid equipment in exchange for their art.

A portion of the resulting 23,000-plus Polaroid Collection will be on display in an exhibition called “Innovation/Imagination: 50 Years of Polaroid Photography” from Saturday through March 16 at the Spencer Museum of Art’s Kress Gallery. The exhibition is organized by The Friends of Photography, San Francisco. Calumet Photography is the national sponsor.

It includes 81 works by more than 50 artists spanning five decades. Some are recognized as photographers; others are best known for work in other media.

John Pultz, curator of photography at the Spencer, applauded the ingenuity of Land’s Polaroid project

“They would give you boxes and boxes of film, and you just had to send them a certain number of prints. I think it was a way to take this product and make sure it was meeting the needs of artists, but it also gave it respectability by showing that serious photographers could use this,” he said. “I think this was a very, very smart thing to do.”

The exhibit showcases art created using a range of Polaroid materials and equipment.

One particularly sleek camera, the SX-70, folded open and closed and would spit out a 3.5-by-4.5 inch photo that developed as you watched it, Pultz said. But if you pressed on it or took a match to it as it developed, you could alter its chemistry, he said.

Lucas Samaras, a photographer featured in the Spencer exhibit, “did amazing self-portraits and portraits of other people in his studio and would use pressure and heat to make the chemicals swirl around and the things look almost like psychedelic art,” Pultz said.

Later, Polaroid developed a 20-by-24 inch camera that photographers could use at one of three studios in the country, he said. An entire room of the Spencer exhibit is devoted to nothing but these giant prints.

“Photographers just loved it, the idea of making a Polaroid that large,” Pultz said.

Polaroid also developed a transfer process that allowed photographers to snap a photo whose emulsion would come off when applied to a piece of paper. The end result looks less like a photograph and more like a lithograph or some kind of print, Pultz said.

The timing of the exhibit is poignant, Pultz said.

“One can think about technologies, how they come and go. Just as we’re embracing one new technology in digital imagery, then we can look back over the whole run of a previous technology sort of watching it from its beginning … to close to its end,” Pultz said, noting that Polaroid lately has been struggling as digital technology becomes more refined. “(The exhibit) has sort of retrospective quality.”