Lightstalking.com

The overview of high lever aperture is: Aperture indicates whether the opening in your lens is wide open or narrow. Your digital SLR communicates with the lens via electronic contacts. You can control the width of the opening by changing the aperture setting from the camera. A small aperture number (2.8) represents a WIDE opening in the lens. A large aperture number (22) represents a NARROW opening in the lens. Aperture numbers follow a standard scale called f-stops. Changing an aperture value by a full stop either doubles or halves the amount of light passing through the lens. Aperture values can be changed in either half stop or third stop increments. the two things we need to know about aperture is that Virtually all lenses can be set to the same narrow aperture (f/36). Not all lenses can be set to the same wide aperture