Benson’s picture of Ronald and Nancy Reagan dancing against a white backdrop is not only the best-known photograph of the president and first lady. ”This,” Benson told LIFE.com, ”is the picture that saved Vanity Fair. That’s not hearsay; it’s documented fact. In 1985 Si Newhouse [the intensely private mogul behind The New Yorker, Vogue, Vanity Fair, and a score of other media properties] was going to close Vanity Fair, and the magazine’s new editor, Tina Brown, pleaded with Newhouse to give the magazine one last chance — because they had this photograph for the cover. Now, of course, people say the picture captures that era — the Reagan Era — better than any other. Maybe it does. But the point is,” says Benson, ”Vanity Fair survived, and this picture gave it a new lease on life. I know — that sounds completely self-serving of me to say that. But it happens to be true.”