A still camera for use with roll film having a row of perforations, one for each film frame, employs a planetary transmission whose planet carrier is rotatable by hand, whose internal gear rotates the takeup reel during transport of film, and whose sun gear can cock the shutter or perform another function while the internal gear is held against rotation. The sun gear is held against rotation by a lever during a first stage of rotation of the planet carrier while the internal gear rotates the takeup reel. A feeler scans the moving film and penetrates into an oncoming perforation to thereby disengage the lever from the sun gear so that the latter can rotate during a second stage of rotation of the planet carrier as soon as the internal gear is arrested due to resistance of the takeup reel to rotate in a direction to collect exposed film. The lever has a tooth which engages complementary teeth of the sun gear during the first stage of rotation of the planet carrier; such teeth constitute an overload clutch which allows the sun gear to rotate against the opposition of the lever in response to rotation of the planet carrier when the latter transmits a predetermined force while the internal gear is also held against rotation. This prevents a tearing of the film and/or damage to component parts of the camera.