Ansel Easton Adams (February 20, 1902 - April 22, 1984) was an American photographer and environmentalist. His black-and-white landscape photographs of the American West, especially Yosemite National Park, have been widely reproduced on calendars, posters, and in books. With Fred Archer, Adams developed the Zone System as a way to determine proper exposure and adjust the contrast of the final print. The resulting clarity and depth characterized his photographs. Adams primarily used large-format cameras because their high resolution helped ensure sharpness in his images. Adams was distressed by the Japanese American Internment that occurred after the Pearl Harbor attack. He requested permission to visit the Manzanar War Relocation Center in the Owens Valley, at the foot of Mount Williamson.