Ansel Easton Adams (February 20, 1902 – April 22, 1984) was an American photographer and environmentalist, best known for his black-and-white photographs of the American West, especially in Yosemite National Park.

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 and the work of those to whom he taught the system. Adams primarily used large-format cameras despite their size, weight, setup time, and film cost, because their high resolution helped ensure sharpness in his images.

Adams founded the Group f/64 along with fellow photographers Willard Van Dyke and Edward Weston. Adams's photographs are reproduced on calendars, posters, and in books, making his photographs widely distributed.

Early life
Childhood
Adams was born in the Western Addition of San Francisco, California, to distinctly upper-class parents Charles Hitchcock Adams and Olive Bray Adams. He was an only child and was named after his uncle Ansel Easton. His mother's family came from Baltimore and his maternal grandfather had a successful freight-hauling business, but squandered his wealth in failed mining and real estate ventures in Nevada. The Adams family came from New England, having migrated from the north of Ireland in the early 18th century. His grandfather founded and built a prosperous lumber business, which his father later ran, though his father's natural talents lay more with sciences than with business. Later in life, Adams would condemn that very same industry for cutting down many of the great redwood forests.

In 1903, his family moved two miles west to a new home near the Seacliff neighborhood, just south of the Presidio Army Base. The home had a "splendid view" of the Golden Gate and the Marin Headlands. San Francisco was devastated by the April 18, 1906 San Francisco earthquake. Uninjured in the initial shaking, the four-year-old Ansel Adams was tossed face-first into a garden wall during an aftershock three hours later, breaking his nose. Among his earliest memories was watching the smoke from the ensuing fire that destroyed much of the city a few miles to the east. Although a doctor recommended that his nose be re-set once he reached maturity, this was never done; as a result, Adams's nose remained crooked for his entire life.

Adams was a hyperactive child and prone to frequent sickness and hypochondria. He had few friends, but his family home and surroundings on the heights facing the Golden Gate provided ample childhood activities. Although he had no patience for games or sports, the curious child took to nature at an early age, collecting bugs and exploring Lobos Creek all the way to Baker Beach and the sea cliffs leading to Lands End, "San Francisco's wildest and rockiest coast, a place strewn with shipwrecks and rife with landslides."

His father bought a three-inch telescope and they enthusiastically shared the hobby of amateur astronomy, visiting the Lick Observatory on Mount Hamilton together. His father went on to serve as the paid secretary-treasurer of the Astronomical Society of the Pacific from 1925 to 1950.