Abstract: A film retrieval system comprises a light source for illuminating a film having marks applied thereon, a photo-detector for detecting light intensity transmitted from the illuminated film, a device for determining a reference in accordance with the light intensity detected by the photo-detector, a discriminator for determining the presence or absence of the mark by comparing the reference determined by the reference device and an output of the photo-detector and, a setting device for setting a detection point of the transmitted light intensity by the photo-detector at any point spaced from a leading edge of the film.

Abstract: A mark detecting apparatus comprises an illuminator means for illuminating a film with marks having density different from the density of its periphery, a plurality of photosensors arranged in the feeding direction of the film, which serve as light receivers for receiving the transmitting light of the film illuminated by the illuminator means to detect the presence of marks, setting device for establishing a reference value on the basis of the maximum value and quasimaximal value among each of the output signals of the photosensors, and discriminator for discriminating the presence of marks by comparing the reference value established by the setting device and the output of the light receivers. With the structure thus arranged, it is possible to establish the binalizing reference value of the photosensors accurately even when the fluctuation of the luminous energy of the light source occurs as well as to correctly establish the reference value reliably even when the base density of the film varies.

Abstract: A film feeding apparatus which feeds a film wound on a supply reel to a take-up means and rewinds the film on the supply reel, comprising: a driving shaft for removably receiving and holding the supply reel on which the film is wound and for rotating the reel; a driving means for rotating the driving shaft in a normal or reverse direction; a judging means for judging a rewinding direction of the film wound on the reel held by the driving shaft; and a control means for controlling the driving means to change a rotational direction of the driving shaft in response to the rewinding direction judged by the judging means, when the film is rewound.