A still camera for use with film having a row of perforations, one for each film frame, has a manually operated film advancing mechanism and a metering mechanism for selectively disabling the advancing mechanism. A lock mechanism retains an intermediate gear at the position where the gear transmits the movement of the manual film advancing member to a film wind-up gear for the film transportation. A sensing pawl releases the intermediate gear and disconnects the same from a transmission train between the manual member to the film wind-up gear to disable the film transportation when the sensing pawl detects a perforation and is slightly moved thereby.