What is aperture? Aperture (also called f-stops) are the areas of lens in which light enters the camera. It is controlled by the diaphragm. Aperture controls the amount of light reaching the film. They are marked, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22 and 32. Not all lenses have all these numbers. Some may start at f-5.6 and end with f-22. Some even have more. They work in stops. From f-1.4 to f-2 is one stop; From f-1.4 to f-2.8 is two stops. Remember, the smaller the number the larger the aperture and vice-versa. For instance, f-4 is larger than f-8, and f-8 is larger than f- 16. Larger apertures allow more lights to reach the film. Each f-stop allows twice as much light as the previous and half as much as the next one. f-4 allows twice as much light to reach the film than f-5.6 but half as much as f-2.8. Think of apertures as a window blind. You get more light with the blind open. As you close the blind, less light enters the room. Lens diaphragm works like a blind. When opened, maximum light goes through the lens and exposes the film. With smaller apertures, less light goes through.

The combination of aperture and shutter speed are related, and effect the exposure value. All digital cameras have exposure modes that automatically control the aperture as well as shutter speed.

F-stops

A diameter of an aperture is measured in f-stops. A lower f-stop number opens the aperture and admits more light onto the camera sensor. Higher f-stop numbers make the camera's aperture smaller so less light hits the sensor. When an aperture is opened up by one f- stop, the amount of light which reaches the sensor is doubled.

F-stops are expressed in three different ways: f/8, f-8, and 1:8

Aperture Priority Mode

Many intermediate and all advanced digital cameras allow you to manually change the aperture. When using aperture priority mode, you change the aperture the shutter speed also is automatically changed to maintain proper exposure. Aperture settings affect depth of field (DOF), how much of a photo is in focus when the camera is focused on the main subject.

When you focus on an object, only the part your lens is focusing on will be sharp. By closing the aperture, you can bring other objects in sharp focus. If you want a blurred background, use larger apertures(f1.8, f2,4 etc). Use smaller apertures(f8, f11 etc)to gain more depth-of-field if you want objects in front and behind your main subject to be in sharp focus.