Abstract: Rollers having attached thereto ribbons of a shutter screen of a focal plane shutter are arranged to have either another roller or a shutter screen take-up shaft fitted therein with a frictional force provided between them. The rollers are provided with an engaging part for engagement with an external member. The degree of parallelism between the slit forming ends of the front and rear screens of the shutter forming a slit for exposure is adjustable by operating the external member to rotate the rollers with a force greater than the frictional force.

Abstract: A focal plane shutter for a camera includes a shutter unit casing for supporting a shutter mechanism. A rotatable body is connected with the shutter for winding up the shutter to a charged position. A shutter driving spring is also connected with the shutter mechanism for driving the shutter and a holding member is coupled with the rotatable body for holding the shutter mechanism in a charged position. A driving shaft carrying a driving gear is coupled to the rotatable body through a transmission gear and a clutch. A spring is coupled with the clutch to urge the clutch in a direction for releasing engagement between the transmission gear and the rotatable body. The driving gear has a plane section on its circumferential periphery spacing adjacent teeth apart so that engagement between the driving gear and the transmission gear is released when the rotatable body is held so that the transmission gear and the clutch can rotate, under the influence of the spring, back to the initial position.