When the sun goes down, Scott Martin’s job begins. He’s a night photographer and instructor in San Antonio, leading workshops to teach curious photogs the nuances of shooting in the dark.

“I had this ‘aha’ moment where I realized that when the world goes to bed there are still all these sleeping giants out there that have this unique relationship with the night,” he says. “All these buildings, all these hidden away places, they are always there yet we so rarely see them in that light.”

Martin was nice enough to...