| 摘要 |
An iris diaphragm provided with a fixed mounting ring and a rotatable setting ring coplanar therewith has a multiplicity of angularly equispaced iris-leaf pairs each including a main leaf and an ancillary leaf articulated to each other at one end, the free opposite ends of the two leaves being respectively fulcrumed on the mounting ring and on the setting ring confronting the same side of the leaves. The generally crescent-shaped ancillary leaf has an arcuate inner edge with a radius of curvature substantially corresponding to the maximum radius of the diaphragm aperture; the main leaf may be of similar configuration of may have a generally elbow-shaped contour.
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