Diaphragm with light blocking element

In an iris diaphragm configured by a plurality of diaphragm blades, partially overlapped, having substantially circular arcuate inner edges with which a variable diaphragm aperture is defined and formed with generally wedge-shaped notches, extending from said substantially circular arcuate inner edges, respectively, with which a variable diaphragm aperture is defined, a stationary support ring for pivotally supporting said diaphragm blades, at first ends of said diaphragm blades, at regular angular separations, and a diaphragm adjusting ring, rotatable relative to said stationary support ring and engaged for sliding movement with each of said diaphragm blades at second ends of said diaphragm blades remote from said first ends, said sliding movement causing pivotal movement of said diaphragm blades to vary said diaphragm aperture from a full diaphragm aperture to a smallest diaphragm aperture with an increase in relative rotation between said stationary support ring and said diaphragm adjusting ring, each of said notches being located between one of said first ends and one of said second ends, the improvement comprising:

• a supplemental diaphragm blade coupled to any one of said diaphragm blades, said supplemental diaphragm blade having a supplemental notch which is similar in shape to but shallower than the generally wedge-shaped notch of said one of said diaphragm blades so as to block up and close off said smallest diaphragm aperture defined by said generally wedge-shaped notches of said diaphragm blades.