You’ve seen the stunning black and white images of Frank Lloyd Wright’s architectural masterpieces that all but leap off the page, but you probably don’t know the photographer who made them.

Pedro Guerrero is the unsung photographer behind many of the most memorable images of Wright’s work, and he is the subject of an upcoming episode of the PBS series American Masters. Below is an exclusive clip in which Guerrero discusses capturing Wright’s geometric buildings.

Guerrero was 22 when he began working for Wright in what was his first photography job. In the documentary, Guerrero recalls meeting Wright and introducing himself as a photographer—something he’d never done before.

“He said, would you like to work for us?”

“And I said, as you can see I don’t know anything about architecture.”

“And he said I’ll teach you.”

Guerrero saw Wright’s architecture as sculpture on a grand scale and photographed it as such. “He was able to photograph it in such a way you could see the reality of the material,” says Bernard Michael Boyle, an architectural historian at Arizona State University. This idea is perhaps most obvious in Guerrero’s photos of Taliesin West, Wright’s home in Scottsdale, Arizona. Guerrero (an Arizona native) made the images with a 4×5 large format camera at high noon. The desert sun was glaring down on the house, casting straight shadows that gave the photograph the feel of a page in a pop-up book. “All the lines were completely straight down,” Guerrero says in the segment featured above, “and if I had waited 5 minutes, the lines would have been different, and it wouldn’t have been as good a composition.”

Guerrero spent 20 years working with Wright until the architect died in 1959. He went on to become a quietly praised icon in the art world, forging similar relationships with artists Alexander Calder and Louise Nevelson, but we still think his work with Wright are his true masterpieces.