For John Duncan, taking pictures became a compulsion the moment he got his first camera, when he was 12 years old. He savored the snap of the shutter, the rolls of negatives, the metallic smell of darkroom chemicals. In 1969, he graduated from Falmouth High School and headed to Woodstock, where he tripped on acid as Creedence Clearwater Revival performed. “In some sense, the only thing that survived the summer of 1969 was my love of photography,” he writes in Take It Easy: Portland in the 1970s, a photo book of his images from the ensuing decade. It captures everything from the Vietnam War–era counterculture to the waning heyday of downtown retail up against the brand-new Maine Mall. Duncan shot while driving his taxi or wandering through neighborhoods or sitting in a bar or a friend’s apartment. He shot all the time — and he still does, some 50 years later. Until recently, his photography was primarily something for himself, a personal record of experiences. It took the idea of a book project to help send him back through his trove of negatives, some of which are now printed for the first time.