however, in a movie camera, it is done through a process by which a shutter opens exposing the film negative to light for a split second (the standard for regular motion in north america is 1/48 of a second, which corresponds to 180 degrees, but shutters with 200 degrees were popular back when the then-available color negative film had an asa of 50; today's color negative film is available with an asa of 500), then the shutter closes blocking light from reaching the negative. once the shutter is completely closed, a claw pulls down the next film frame of negative film by the sprocket holes into the film gate and the process begins again. a movie projector works in a similar way.