An adjustable diaphragm, reminiscent of the iris of the eye in its action, by which the diameter of an approximately circular opening may be controlled, as for regulating the aperture of a lens; it consists of a number of movable thin curved plates fastened at regular intervals around the inside of a ring, the positions of which are simultaneously adjusted by a single knob on the outside of the lens. It is used in cameras and microscopes.
A mechanical device capable of varying the effective diameter of a lens.
usually mounted under the condenser this controls the amount of light converging on the specimen by opening or closing the leaf diaphragm.
diaphragm consisting of thin overlapping plates that can be adjusted to change the diameter of a central opening
an adjustable device that is fitted into the barrel of the lens or shutter housing
a series of thin, curved, metal blades that overlap each other and is fastened to a ring on the lens barrel or shutter housing
Set of pivoted leaves built into the lens which by means of an external control can increase or decrease the effective lens opening or aperture (q.v.). Oil some cameras the operation of the iris may be semi automatic or automatic, as when the lens must be fully open for focusing on a ground glass screen, but close down to a pre selected aperture for exposure.
An adjustable diameter hole which fits the gate of a profile spot to alter the beam angle.
A mechanical aperture (opening) designed to smoothly change the aperture size by use of a lever arm. For lenses, the iris changes the effective diameter and thus controls the amount of light through the lens.