Which camera control governs the size of the lens opening to regulate light?

Which camera control governs the size of the lens opening to regulate light?

• A. Shutter
• B. Zoom
• C. Focus
• D. Iris

Answer: (D)

The iris is what controls the size of the lens opening to regulate light. It acts as the diaphragm inside the lens, opening wider to let in more light or closing down to restrict light. This directly affects exposure and depth of field: a larger opening brightens the image but yields a shallower depth of field, while a smaller opening darkens the image but increases depth of field. The shutter governs how long light hits the sensor, zoom changes the focal length for framing, and focus adjusts sharpness, so none of these directly alter the lens opening or the amount of light, unlike the iris.

The iris is what controls the size of the lens opening to regulate light. It acts as the diaphragm inside the lens, opening wider to let in more light or closing down to restrict light. This directly affects exposure and depth of field: a larger opening brightens the image but yields a shallower depth of field, while a smaller opening darkens the image but increases depth of field. The shutter governs how long light hits the sensor, zoom changes the focal length for framing, and focus adjusts sharpness, so none of these directly alter the lens opening or the amount of light, unlike the iris.