Abstract: A shutter-plate operating means for a camera is arranged for sliding and pivotal movement within a shutter housing and is spring-biased out of a cocked position, said operating means and a shutter plate being provided with interengageable cam surfaces, such that upon sliding movement of the operating means into a cocked position the cam surfaces will co-operate to cause the operating means to pivot to allow it to pass beyond the cam surface of the shutter plate, and such that upon release of the operating means from its cocked position, interengagement of the cam surfaces will cause the shutter plate momentarily to open a shutter aperture. Preferably the shutter plate operating means comprises a single, integrally formed shutter plate operating element which is generally planar, is arranged for sliding movement within the housing and includes the cam surface for operating the shutter plate, said cam surface being mounted on a resilient integral extension of said shutter plate operating element.

Abstract: A camera mechanism in which a shutter plate operating member is slidably mounted for movement between a cocked position and rest position and biased by biasing means into said rest position, and in which actuator means is provided for effecting said sliding movement of said shutter plate operating member, said actuator means being adapted to be connected to a film wind-on device of a camera, wherein said actuator means comprises a cam mounted for rotation in said mechanism and an abutment surface on said shutter plate operating member for cooperating with said cam, so that, in use, rotation of the cam causes said shutter plate operating member to move from its rest position to its cocked position against the urging of said biasing means, said cam being provided with force-varying means whereby greater force is needed to rotate the cam over an initial part of the cocking stroke of the shutter plate operating member than is needed for a final part of said cocking stroke.