Karsh immigrated to Canada from the Ottoman Empire (now Turkey) at 16, leaving his family to live with his uncle, a photographer. After an apprenticeship with portrait photographer John Garo in Boston, he took over his own studio, eventually capturing the attention of Canadian Prime Minister Mackenzie King, who helped arrange portrait sessions with visiting dignitaries.

Karsh approached all of his subjects in the same way, from Mother Theresa to unknown people who sat for the photographer to gift a portrait to a spouse. He traveled regularly, preferring to photograph people in their own environments to maximize their level of comfort in front of the camera. And as much as possible, he spent time getting to know them before even laying a finger on the camera.

For the subject, Fielder says, this prelude to the portrait “was just a casual conversation. For him, he was always looking for something that was real and genuine.” Whatever he determined that truth to be—Churchill’s determination or the Pope’s holiness—he would be prepared to snap his shutter the moment it manifested in his subject’s face or eyes or hands.

“People want to present themselves a certain way and that’s not what he was looking for,” says Fielder. Karsh was looking for the essence of his subjects, a point he emphasized in a lecture in 1951. “If I succeed, the portrait should tell not just that X has a heavy jaw and Y drooping eyelids,” he told an audience at Kent State University. “It should convey the message that here we have a man of willpower, iron determination, singleness of purpose—that here is a thoughtful, perhaps calculating, perhaps careful man who weighs and ponders before he makes up his mind.”