In the first weekend of May, after some late snowfall had cleared, the George Eastman Museum in Rochester, New York held the fifth annual Nitrate Picture Show. Nitrate film stock, manufactured until 1952, was the dominant medium on which all kinds of films were shot and projected for roughly the first sixty years of cinema’s lifespan. Now, it is scarcely projected. Devotees of the medium insist on its unparalleled beauty, its depth of colour, its dark blacks and brilliant whites. They will tell you you’ve never really seen a classic film—Casablanca, Black Narcissus—until you’ve seen it on nitrate. They compare it to a religious experience.