The user of the camera moves an input component to supply film-transport force. A rotary transmission transmits film-transport force fo the input component to the film in the camera, and includes first and second output components. When the input component is moved, the first output component is arrested and the second non-arrested, and then the second output component is arrested and the first non-arrested. A locking structure moves from a locking position arresting the first output component and an unlocking position releasing the first output component. A sensing mechanism responds to film frame advancement by entering into a film perforation, causing the locking structure to move to the unlocking position and causing the second output component to become arrested by the resistance of the film to transport. The transmission includes a gear driven by the input component and driving the second output component and displaceable mounting member mounting the gear for both rotation and displacement. The displaceable mounting member constitutes the first output component of the transmission.