Chapel Hill photographer John Rosenthal has shown his distinctive photographs often and widely for many years, but this week he opens the most significant exhibition of his career. Thursday, Aug. 28, marks the third anniversary of the last day of life-as-they-knew-it for the residents of New Orleans, and Rosenthal will be at the African American Museum, in the Treme section of that city, for the first full showing of Then: Absence, his portfolio of 44 photographs of the Lower Ninth Ward taken last year. In most cases, even the wrecked physical fragments of this community depicted in the unpeopled photographs no longer remain. After Hurricane Katrina, the bulldozers. Then: Absence.

“At the core of every picture is human loss,” said Rosenthal last month in an interview at the UNC Center for the Study of the American South, where two dozen of the large color photographs were on view. “I had to work against the beauty of the landscape, because what’s going on in the Ninth Ward is a crime, and my point is not some cheerful one.”

Rosenthal, who is as well known for his voiced thoughts (from 1986 through the 1990s he contributed to WUNC-FM and NPR, producing nearly 500 observant, philosophical commentaries) as for his widely exhibited images, had not intended to photograph post-Katrina New Orleans. It was more than a year after the storm when he returned to the city, and then it was to visit friends. “I don’t think it’s my business to photograph people’s tragedies,” he says, noting that photography critic Susan Sontag’s scathing remarks about class tourism have always remained with him. He refuses to be that tourist, the middle-class white man hung about with expensive camera equipment, looking at a poor person and making a living off it: “I don’t like the claim strangers make on strangers when they photograph them.” Not intruding, he says, is his ethos.

But by the time he got to the Lower Ninth Ward in 2007, there was no one there to intrude on. The big frenzy was over, and it was, he says, “just me and the tour buses.” (Sontag must be turning over in her grave at tour operators profiting from others’ impoverishment in this extreme example of class tourism.) Rosenthal could hardly believe his eyes. Where was the slum of poverty, depravity and crime that the mass media had been going on about? What he was seeing was the remnant of a community of modest houses, businesses, churches and schools. It had not been wealthy, but it had been vibrant. He was possessed by an overwhelming need to photograph, and quickly. Between February and October 2007, he shot hundreds of frames, returning to the city again and again. “I’m at war with these demolition trucks! I’ve got to archive this neighborhood because it is not going to be there.” He saw no other photographers as he roamed the empty streets and pushed into wrecked buildings, deep in alluvial mud still wet after two years.

Some of the most powerful images in the series were made in the new Louis Armstrong School. The school building itself wasn’t newit was an old school, rehabbed, furbished up and renamedbut it had opened only days before the water came. When Rosenthal came on it, the school was locked behind a 10-foot chain-link fence, dangerous and off-limits. He squeezed his tripod and himself, Mamiya camera in hand, through the slack in the gate.

“I’ve never been in an eerier space,” he says. “It was the kind of thing you experience only in the movies … to walk into a school like that that had stopped dead.” In all the rooms, the clocks read 3:47, marking the moment when the rising water met the electric supply. Each room, so lovingly prepared for its young students, was another panorama of waste, veiled in mold hanging from the high-water line. Rosenthal had 30 frames of film with him; he made three exposures each of 10 subjects in 45 minutes. “I was talking to myself, trying not to make any mistakes, because I knew I would never get back. I was shaking … in the presence of a sustained revelation.”

The John Rosenthal of the perfect exposure and precise focus abandoned himself to the conditions. With only the dim available light and without a shutter release cord, he made pictures of delicate clarity that seem to dissolve under your eyes, even while scalding you with the artist’s sorrow and rage. “The poor care about their places and their children just as much as we do,” he says. “These photographs are a reprimand to how we think about the poor.” Rosenthal had hoped to show his pictures alongside photos from before, ones that showed presence and life. But they were gone. All the decades of negatives in all the photo studios, and all the photograph albums in all the houses in the Lower Ninth Wardall perished. The images of Then: Absence are among the few physical records that can show even the shadow of the life that was in the Lower Ninth.

“When you can point your camera anywhere, where you choose to point it is who you are as an artist,” says Rosenthal, comparing the photographer’s choice of subjects to that of the poet. Rosenthal has chosen to look at a variety of subjects over the years; the photographs that eventually result from his deep looking are always serious. And as philosopher-novelist Pascal Mercier asks, “Can there be anything more serious than poetic seriousness?” Light-poems pared of excess, luxurious in their essentials, Rosenthal’s images may be mysterious, or humorous, but they are always serious in their empathy and sympathy for humanity and our works, whether interior or exteriorour bodies, our dreaming souls, our architectures and arrangements. Rosenthal’s superbly crafted poetic images are the works of a refined aesthetic sensibility which demands that beauty reveal itself in any subject.

“I want to do just the opposite of documentary photography,” says Rosenthal, who became an accidental documentarian the day he first confronted the empty Lower Ninth Ward. The whole point in this work, he says, was to take himself out of it as much as possible, “to take out the artsy-ness. It couldn’t be art stuffit had to be part of the discourse about poverty in this country.” He didn’t want these pictures to be about his vision or his expressive powers. Like Walker Evans, whose work he admires, Rosenthal tried to take a just-the-facts-ma’am approach, to present hard information straight, without ambiguity or judgment or condescension. Yet these documents are the most poetic pictures of his decades as a photographer. Their formal beauty seduces you, opens you up to the body blow of their cumulative content and the uppercut of shame at enjoying these aesthetically exquisite views of new ruins. “Art at its best is always a rebuke,” says Rosenthal.

“I’m delighted they turned out to be good photographs,” he continues, torn between art and the fury that often besets documentarians. “But right now the back story is what concerns me: The ruination of a neighborhood … If this was just a flood, the story would be different. This was man-made and promises have not been kept. This is a tragedy.”

To view small images from the Ninth Ward portfolio online, and to read Rosenthal’s essay about them, go to Rosenthal is represented locally by Tyndall Galleries and Ann Stewart Fine Art. Then: Absence will be on view at the New Orleans African American Museum Aug. 28-Oct. 18. Another set of prints is on view at Boston’s Panopticon Gallery through September. The portfolio will be shown at N.C. State’s Gregg Museum in 2010.

A different series of post-Katrina photographs, by photographer Thomas Neff, an art professor at Louisiana State University, opens Thurday at UNC-Chapel Hill’s Center for the Study of the American South. Entitled Holding Out and Hanging On: Surviving Hurricane Katrina, the exhibit is open Thursdays through Sept. 30.