It is said that Oscar Barnack was the first to use 35mm film in a still camera in 1913. He is sometimes referred to as the grandfather of 35mm photography because of this fact. Positive film makes up a 35mm slide. It is commonly found mounted in plastic or cardboard frames. Slides were commonly used in art classes and to teach art history because of the color accuracy they provided when viewed through a projector. Today, 35mm is still the most popular film used by both professional and amateur photographers because of its convenience, inexpensive pricing structure and the strength of image quality produced.