Abstract: A locking mechanism and method are provided for use in any photographic system which uses film cartridges. One embodiment includes a drive lever and an actuator which prevent movement of a slider door release, thus preventing unlocking of a film door when a film spool is improperly parked within a cartridge. Proper parking is determined by the position of a drive spindle, which operatively engages the film spool. In another embodiment, an actuator contacts a drive spindle and selectively engages a light lock driver. When the light lock driver is not engaged, the slider door release is moveable to unlock the film door. When the light lock driver is engaged, the slider door release is not moveable to unlock the film door. A user controlled mechanism may be included to properly park a film spool in the event that the photographic system improperly parks the film spool. An electro-mechanical switch may be included for properly parking the film spool.