Ansel Adams was one of the most socially engaged artist-activists of the American West. His photographic practice and thinking were informed by the writings of 19th-century transcendental philosophers Henry David Thoreau and Ralph Waldo Emerson. Advocating a life close to nature, he was an early supporter of the environmentalism that Theodore Roosevelt had championed during his presidency. Creatively engaging with dialectical reversals between visionary romanticism and political pragmatism, Adams photographed with a large format high-resolution apparatus the cosmic consciousness of Yosemite’s grand mountains, melancholic forests, falling rivers, operatic geysers, and sci-fi moon rises. He experimented with shutter speed, aperture size, long exposure, and various filters to blacken the sky, illuminate the moon, and give his pictures stunning contrasts. His choice for the lens setting f/64 (the smallest aperture of the lens) invests his pictures with critical depth, offering an extended state of observation. A dedicated wilderness preservationist, Adams depicted a land barely touched by humans. In light of recently escalating ecological disasters, Adams’s visionary exploration of our planet remains acutely contemporary in focus.