"Light by the Water," by Plein Air Peconic, in Sag Harbor SOUTHAMPTON, N.Y. - One afternoon last month, Susan D'Alessio, a landscape painter, stood at her easel on a sandy spit of land overlooking Scallop Pond, in the Southampton hamlet of North Sea. "There's two big babies in there," she said, pointing to an osprey nest atop a tall pole in a salt marsh nearby. A couple of minutes later, as if on cue, a pair of swans glided by in the pond. Ms. D'Alessio, 59, of Bridgehampton, was working at the almost impossibly idyllic site with two fellow members of Plein Air Peconic, a group of a dozen painters and photographers based on the South Fork of Long Island's East End. "At Scallop Pond, we can all come, and there's unlimited space for painting," she said. With such picturesque vistas of water, field and farm, the East End has been a magnet for generations of artists. The members of Plein Air Peconic, however, aim not just to capture the landscape, but also to help preserve it. The group is affiliated with the nonprofit Peconic Land Trust, which has worked with landowners, municipalities and other organizations to protect more than 10,000 acres of natural land and working farms, mostly on the East End, from encroaching development. "We consider ourselves field ambassadors" for the trust, said Gordon Matheson, a Southampton landscape painter and onetime textile designer who rounded up some fellow artists to found Plein Air Peconic in 2006. For its name, the group drew on the French phrase en plein air, referring to painting outdoors, and Peconic, to reflect an artistic focus on the area around the Peconic Bay, Mr. Matheson, 68, said. In most of the group's exhibitions, at least half of the art depicts land conserved by the Peconic Land Trust, as well as other groups, to bring heightened awareness of conservation to a new, art-oriented audience, Mr. Matheson said. Its current show, "Light by the Water: Coastal Landscapes of the Sag Harbor Area," which runs through July 9 at the Sag Harbor Whaling and Historical Museum, is an exception. According to Casey Chalem Anderson, 56, a Plein Air Peconic artist who lives near the village of Sag Harbor and coordinated the exhibition, "Because it takes place in the whaling museum, we definitely emphasize the coastal area." A percentage of sales from the exhibition will benefit the museum and, as with all Plein Air Peconic shows, the land trust. A free reception with the artists will be held at the museum on July 1, from 11 a.m. to 1 p.m. Visitors can expect "the gospel of the Peconic Land Trust and conservation," as Mr. Matheson put it, to be served along with the coffee. The artists benefit, too, from the relationship, especially by gaining permission through the trust to work on privately owned, conserved property that would otherwise be off limits. Among the trust's activities is drawing up conservation easements, in which landowners gain tax benefits by agreeing to prohibit certain kinds of development on their property. The trust - founded in 1983 by John v.H. Halsey, 60, a 12th-generation East End resident - also publicizes the artists" exhibitions through its own member list. "They help us sell art, and we help them sell conservation," Mr. Matheson said. Rebecca Chapman, a vice president of the trust, who worked with Mr. Matheson to develop the alliance, said, "It's a symbiotic relationship." Scallop Pond is a favorite painting spot, surrounded by lands owned or otherwise conserved by the Peconic Land Trust; a private estate; and the Scallop Pond Preserve, a salt marsh under the aegis of the Nature Conservancy. A bumpy drive down a narrow dirt road surrounded by high grass leads to the sandy area where Ms. D'Alessio and her two fellow painters, Ms. Anderson and Eileen Dawn Skretch, were at work that afternoon last month. Ms. D'Alessio had been at it since noon. "The clouds have changed," she said, but it didn't matter: "I'm aiming for the feel of the summer day." The gloomy weather forecast notwithstanding, the day was indeed summery. "Picture-perfect," Ms. Anderson declared. Nearby, Mrs. Skretch, wearing a Peconic Land Trust baseball cap with a scallop-shell logo, was painting on a small piece of wood whose natural striations were incorporated into her work. Speaking by phone the previous day, Mrs. Skretch, 58, a Southampton resident who grew up on an East End farm, recalled the landscape of her childhood. "Beyond Bridgehampton, it was just fields," she said. All you could see was fields, dotted with farmhouses, and you could see the band of ocean beyond the farmhouses. Much of that acreage is now developed. Though Mrs. Skretch said she understood why many people sold their property in the heated Hamptons real estate market, she added, "I'm still a farmer's daughter, taking my heritage one step further" through her painting. Kathryn Szoka, a photographer and an owner of Canio's Books in Sag Harbor, arrived late, but soon hopped on the bed of her red pickup truck to take shots of the osprey nest. Ms. Szoka, 56, who has documented the changing character of the area with a photographic series called "Vanishing Landscapes," said by phone a few days later that the conservationist thrust of Plein Air Peconic was the glue that bound its diverse artists. "It is a uniting interest," she said. And it gives a larger goal to the work we do. "Light by the Water: Coastal Landscapes of the Sag Harbor Area," by Plein Air Peconic, runs through July 9 at the Sag Harbor Whaling and Historical Museum, 200 Main Street. Admission, $6. sagharborwhalingmuseum.org; (631) 725-0770. Another show of the group's work will be held July 3 through 29 at the Westhampton Free Library, 7 Library Avenue, Westhampton Beach. (631) 288-3335; westhamptonlibrary.net.