Apparatus of preventing bound of diaphragm blades in camera

In a diaphragm actuator of a lens of a camera, comprising a stationary support ring, a blade ring which is rotatable in and relative to the support ring and which has a plurality of diaphragm blades rotatable thereto by means of pivots, said diaphragm blades being movably connected to said support ring so that the rotational movement of the blade ring relative to the support ring causes the diaphragm blades to open and close in order to control a diaphragm opening defined by the diaphragm blades, and an angular displacement limiting member which limits the angular displacement of the blade ring to control the diaphragm opening in accordance with a predetermined aperture F number of the associated lens, said blade ring being rotated until it is brought into contact with the limiting member when the diaphragm blades are closed, the improvement comprising an apparatus for preventing the blade ring from bounding when the blade ring comes into contact with the limiting member, said bound preventing apparatus comprising a bound preventing ring which is rotatable relative to the support ring and which comes into contact with the blade ring to brake the movement of the blade ring immediately before the blade ring comes into contact with the limiting member.