aperture diaphragm

ap·er·ture di·a·phragm

a metal device that limits the area of the beam emerging from an x-ray tube.
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The substage condenser must have a continuously variable circular aperture diaphragm (A stop) and be capable of true Kohler illumination for the full spectral range of 350 to 950 nm.
In addition, newly adopted 9-blade aperture diaphragm help produce bokeh with a smooth, circular shape.
Distortion is small in lenses with constructions symmetrically configured on both sides of the aperture diaphragm, but is likely to occur in lenses having asymmetrical configurations.
Each Canon Cinema lens is equipped with an odd-numbered 11-blade aperture diaphragm, which is ideally suited to achieve creative depth-of-field manipulation and pleasing "bokeh" effects of cinematographic quality.
The lens features a nine-blade curved aperture diaphragm to provide beautiful, blurred backgrounds even at full-zoom range.
Seven-blade aperture diaphragm that helps to create smooth and round bokeh effects.
A circular aperture diaphragm that produces an attractive smoothness in out-of-focus areas.
The LM and LV series feature two precision photo-etched measuring lines, changeable field and aperture diaphragm, and dual leafspring indenter supports for centered indentations, greater accuracy and excellent repeatability.
Each lens is equipped with a newly designed 11-blade aperture diaphragm for soft, attractive blur characteristics, making them ideally suited for cinematographic applications.
Nikon's AZ100 Multizoom microscope has a zoom aperture diaphragm located at the back focal plan of the objectives lens resulting in a consistent telecentric image across the entire zoom range.
The illuminator changeover turret and aperture diaphragm, as well as the illuminator voltage control, have all been motorized for accurate reproduction of illumination so images can be captured using consistent illumination.
2L II USM lens offers high-speed manual focus, distance encoding for E-TTL II flash, and a circular aperture diaphragm that improves the appearance of background areas.