In June 1955, Adams began his annual workshops at Yosemite. They continued to 1981, attracting thousands of students. He continued with commercial assignments for another twenty years, and became a consultant, with a monthly retainer, for Polaroid Corporation, which was founded by good friend Edwin Land. He made thousands of photographs with Polaroid products, "El Capitan, Winter, Sunrise" (1968) being the one he considered most memorable. During the final twenty years of his life, the 6x6 cm medium format Hasselblad was his camera of choice, with "Moon and Half Dome" (1960) being his favorite photograph made with that brand of camera.