Keeping a boundary between one’s professional and private life may be wise, but when it comes to portrait photography, the better you know your subject the more time he or she gives you. The Turkish photographer and poet Lütfi Ökök freely mixed work and pleasure, continually arranging his friends—who happened to be leading artistic and literary figures—in front of his camera. By repeatedly photographing the same people, Ökök captured time’s passage, and with it the changing landscape of his subject’s inner world. Nearly 90 portraits are on view, including photographs of Samuel Beckett and Nadine Gordimer. —J.V.