Alfred Stieglitz (1846–1946) remains one of the most central and influential photographers of the twentieth century. He championed what became known as 'straight photography', a vision of the photograph that sought to establish it as an art form separate from painting and basic to its status as a 'modern' medium. He was also a major figure in the modernist movement in the New York of the 1900s and, through his galleries and publications, played a crucial part in the development of both American art and photography. Stieglitz promoted, published and exhibited much of the best photography of the period in his role as editor of the now legendary magazine Camera Work, and through his galleries, and wrote extensively on photography throughout his career.

With a career straddling two centuries, Stieglitz's work bridges their different photographic styles. He was born in Hoboken, New Jersey, but studied in Germany, where he was first drawn to photography, and in the 1880s he travelled around Europe taking pictures. At the age of 24 he won a British photographic competition judged by P.H. Emerson, the first of the 150 prizes he was awarded in his lifetime. On his return to New York in 1889 he began exhibiting his own work and writing on photography, specifically on the movement known as Pictorialism, which influenced his early style. However, he soon came to reject the retouching and other forms of manipulation used by the Pictorialists to create a painterly softness of effect in favour of using natural means such as mist, rain or snow to achieve the desired result. His work evolved progressively towards this ideal of 'pure' photography, and writing in 1922 he stated 'My aim is increasingly to make my photographs look so much like photographs that unless one has eyes and sees, they won't be seen – and still everyone will never forget having once looked at them.' That year he began his extended series of cloud photographs, which he considered to be 'equivalents of my basic philosophy of life', translating the Symbolist notion of equivalency into photographic expression. His later work also includes portraits, studies of his wife Georgia O'Keeffe, photographs of Lake George and views of New York City.