Aperture

The aperture is a circular opening inside of the lens. It's diameter is varied by a group of metal flower petal like parts. When the button on the camera to take a picture is pressed all of the petals move together to change the diameter of this opening so that it is set to correspond with the light. If it is a very sunny day the meter will set the aperture to a very small circle perhaps the size of the head of an average carpentry nail. If it is a very overcast day the meter will set the aperture to a very large circle perhaps half the size of the diameter of the lens. If the aperture is open too little the photograph will be too dark. If the aperture is open too much the photograph will be too light. Many cameras allow the photographer to choose an aperture. The advantage of this type of camera is that by varying the aperture the photographer can control how much will appear in focus in addition to what is seen in focus through the viewfinder in the finished photograph. Aperture settings are also called f stops. The term "stopping down" refers to setting the aperture to a smaller circle

45 maximum amount of focus

32

22

16

11

8

5.6

4

2.8

2

1.4 minimum amount of focus