An iris diaphragm comprising an annular base, an annular rotatable element and
a number of leaves which can be mounted to form a variable aperture, each leaf
extending between the base and element and being connected thereto in a pivotal
relationship, is characterised in that a first end of each of said leaves is pivotally
connected to an opening provided on the element or base by means of a burst hole
joint, and a second end of each of said leaves being rotatably secured in a sliding
relationship to a slide provided on the base or the element by means of a slide
pin secured to the leaf.
