What is an iris in lighting design?

An iris in lighting design refers specifically to an aperture device used in a profile lantern, which is also known as a spotlight. This device allows the designer to control the shape and size of the light beam emitted from the fixture. By using an iris, designers can create sharp edges around the light projection, manipulate the intensity of the light, and achieve precise focus for specific stage areas or elements. The iris can be adjusted to change the diameter of the opening, thereby altering the beam spread without changing the lamp or other components of the lighting fixture.

The other options relate to different lighting components: dimming devices control the brightness of lights, color filters adjust the color of the light being emitted, and lenses generally serve to broaden or direct the light quite differently from how an iris operates.