The guitarist revs up his amp, giving the universal signal that a punk rock concert is about to begin. Ahmad Zaghal digs for the iPhone in his pocket and shouts between the power chords: “Am I facing the right way?”

He’s half-joking. Because he’s blind. But he’s half-serious. Because he’s on Instagram, the photo-sharing social-media service that has — among other things — helped turn every concertgoer into a concert photographer, including Zaghal. “This is what happens when someone who can’t see a thing decides to shoot concert pics,” he’s written on his profile page. “Captions only indicate what I think I’m shooting.”

Last time Zaghal was here at the Rocketship — a group house in 16th Street Heights where underground rock bands make urgent noise on a cold basement floor— he thought he was shooting local punk quartet Priests. Instead, Zaghal went home with some blurry snaps of the pipes and paneling.

“I thought there was some kind of stage here,” he says. “But my friends are pretty honest. They’ll tell me, ‘Oh, you got a bunch of pictures of the ceiling.’ ”

When his subjects don’t elude the frame entirely, they’re often truncated, decapitated or abstracted into blurry smears of pixels. The least successful images become the most successful. Which is beautiful. And hilarious.

“It’s a totally funny idea,” Zaghal, 31, says. “And now people are taking it more seriously. And that’s great. Maybe there is a point to this!”

Point or no point, Zaghal is dedicated to pursuing this project — some thing he refers to as both “a joke” and “an experiment.” He attends roughly 20 concerts a month, always arriving in time to snag a spot up front. Once the band gets started, he hoists his iPhone to his ear and listens. Screen-reading software tells him when he’s selected the camera function. Then, he points and shoots. If there’s nobody to chat with between sets, he’ll caption the images and post them to Instagram straight from the gig.

That isn’t the case at last Tuesday’s Rocketship show. Between bands, Zaghal is hanging out in the front yard, chatting with the singer of Neonates, a band he photographed in August, and the guitarist of Fell Types, whom he’s about to snap in a few minutes.

The social demarcation line that usually separates bands from fans is nonexistent here — an attitude of acceptance and inclusion passed down from Washington’s storied hardcore punk scene. Which is to say, the blind guy shooting concert photos is really no biggie.

“I don’t get asked about [being blind] as much as you’d expect,” Zaghal says. “Maybe that’s what keeps me coming to these shows, subconsciously. . . . I never thought about it.”

An alterna-rock beginning

Zaghal’s taste gravitates toward the vanguard, but his first concert was anything but — Limp Bizkit, Everclear and other alterna-rockers at the 1999 HFStival at RFK Stadium. After that, he dipped his toe into the jam band circuit but didn’t start attending concerts regularly until 2003.

“I think there was a bit of trepidation to venture out,” says Zaghal, who has been blind since birth. “And I thought to myself, ‘Why do that?’ I’m just as capable of getting out and going to a show like anybody else. If you want to do something, go ahead and do it.”

In 2008, he won a raffle granting him year-round admission to the 9:30 Club, where he attended more than 175 concerts in 2009. He’s still a regular, but he says his favorite performance spaces are the smaller ones, including scrappy D.I.Y. venues such as the Rocketship. “It’s a more visceral experience,” Zaghal says, “being right there, being a few feet from the band.”

Zaghal has been quick to befriend like-minded pals at these cozy shows, including Valerie Paschall, a local music journalist who’s as ubiquitous in the scene as Zaghal. “I go to a hundred-plus shows a year,” Paschall says, “and he’s at most of them.”

In late August, Paschall lobbed a question into the Twitterverse: Did she really need to follow the digital lemmings and join Instagram? Zaghal replied: “No. But consider the source of this tweet.”

“I thought that was the best response,” Paschall says. “Six days later, he sends me a message saying, ‘You know what? I should start an Instagram account. I should take photos at concerts.’ I said, ‘Yeah, that would be genius.’ ”

Since then, Zaghal has posted 204 concert photos, turning some of his subjects into Instagram followers along the way — Elisa Ambrogio of noise-rock band Magik Markers, Baltimore outsider-folkie Lexie Mountain, members of local bands Cigarette and the Plums. The response has been almost unanimously positive. An artist friend of Zaghal’s is even plotting a series of paintings based on his photos.

“Some of the pictures he’s coming up with are as good as or better than iPhone photos taken by people who can see what they’re doing,” Paschall says. “An interesting commentary, I think!”

One venue to another

Some nights, Zaghal will drop in on more than one gig, hailing cabs from one venue to another. But once the music stops, he uses MetroAccess — Metro’s door-to-door paratransit service for people with disabilities — to get back to Germantown, where he’s living with his parents.

He says his folks have been nudging him away from the nightlife, toward a career and a family. “They think I overdo it,” he says.

He has a B.A. in criminology from the University of Maryland but has spent the past few years moving from job to job. He’s trained federal employees in the use of screen-reading software, done research at a nonprofit and now works at an office in Damascus, booking training sessions for child-care professionals. It’s the kind of job that allows him to wear band T-shirts to work and listen to music on his computer. But not on Pandora.

“With these streaming services, I think it’s another way for these labels to maintain a stranglehold on the market,” Zaghal says. “And honestly, I can’t really use them because they’re not all that accessible to screen-reading software. Pandora, Spotify, Rdio — they’re not user-friendly to blind people.”

Online, Zaghal discovers music most often through Twitter and Bandcamp, an online music retailer friendly to independent artists. He says the explosion of the music blogosphere 10 years back put a world of music at his fingertips.

Today, he navigates the physical world with similar ease, often leaving his cane at home. “I like to travel light,” he says — even if that means descending a precarious staircase to see a punk band stomp around a cluttered basement. “It’s a set of stairs,” he says. “It’s like every other set of stairs.”

On a recent Thursday night, there are no stairs to navigate at the Atlas Performing Arts Center, which is hosting Sonic Circuits, an annual festival of experimental music now in its 13th year. It’ll be a loud one. The kind that makes your bone marrow softly vibrate. The kind Zaghal particularly enjoys.

He always wears earplugs to protect his hearing, but one of his most cherished concert memories was catching My Bloody Valentine, the Irish rock band that sounds like a melodic plane crash.

“I’ve been telling people that the loudness [was] more of a physical thing than an auditory thing,” Zaghal says. “I’ve never felt anything like that at a show, before or since.”

At the Sonic Circuits performance, the most powerful vibrations come during a set from SEMISOLID, the stage name of local electronic musician Chester Hawkins. Clad in a Motorhead T-shirt and sipping a bottle of beer, Hawkins uses a tabletop of synthesizers to create ominous swells of synthetic sound. When the music begins to resemble a video arcade practicing meditative breathing, Zaghal reaches for his iPhone.

“I wait for a good, intense moment,” he says of the instant he decides to snap a photo. “A peak of some sort.”

That might be what gives these photographs their latent power. They aren’t photos of bands making music. They’re portraits of air in a room, vibrating powerfully.

He raises his arm, points toward the sound and clicks.

Follow Ahmad Zaghal on Instagram at @ahmadmzaghal