What does aperture on a lens refer to?

• A. The distance between the lens and the sensor
• B. How big the opening contact is on the lens
• C. The weight of the lens
• D. The number of aperture blades

Answer: (B)

Aperture is the size of the opening inside the lens through which light passes to reach the sensor. This opening is controlled by the iris diaphragm and can be made larger or smaller. When it’s opened wider, more light enters, producing a brighter image and a shallower depth of field; when it’s narrowed, less light enters, producing a darker image and a deeper depth of field. The number of aperture blades can influence the shape of the opening and the look of bokeh, but aperture itself is about how large that light path is. Other factors like the distance from lens to sensor or the lens’s weight aren’t what aperture describes.