Julia Margaret Cameron began making photographs at the age of 48, when her daughter presented her with a camera, writing "It may amuse you, Mother." From her home in Freshwater, on the Isle of Wight, Cameron convinced not only her servants to pose for her but also some of the most famous people in British society, including Charles Darwin and Poet Laureate Alfred Lord Tennyson. The subject of this portrait, Sir John Herschel, was primarily known as an astronomer, but is noteworthy in the field of photography for several innovations. Among other things, he suggested the use of sodium hyposulfite to arrest, or "stop," the developing image so that it would not continue to darken beyond recognition. Cameron's image of Herschel, with his hair in disarray, seems to suggest his inner genius. The print was hand-coated by Cameron, and it was made by the very messy and smelly wet-collodion process that relied on large glass plates as negatives.