Fairfield Porter: Modern American Master (Parrish Art Museum, 279 Montauk Highway, Water Mill, N.Y., ongoing). For much of his adult life, Fairfield Porter lived and painted in Southampton, and many of his paintings belong to the permanent collection of the Parrish, which is now hanging them regularly rather than sporadically in its new building. Anyone interested in the work of one of America’s most insufficiently recognized modern masters, a lifelong realist who was nonetheless deeply influenced by abstract expressionism, should hasten to Water Mill and partake of this important show (TT).