Understand Aperture (Basic Photo Knowledge)

Aperture

Aperture is the amount of light that is allowed to past through the lens to the camera sensor.  Aperture is expressed in f/number (e.g. f/2, f/2.8) which is a fraction. f stands for the focal length of the lens.  Focal length is (?).    / means divided by.  Hence, if the lens has a focal length of 100,  f/2 indicates that a diameter of 50mm is opened for the lights to go through the lens. The smaller the number of the f/number, the more light is passing through the lens, hence f/2 has more light than f/2.8 (Note: 2 is smaller than 2.8). The following is a full stop scale of f/number.

f/No.	0.7	1.0	1.4	2	2.8	4	5.6	8	11	16	22	32

Each of this value represents one time the amount of light either more or less in quantity. In order word, each larger number has two times light than the smaller number. For example, f/1.0 has two time more light than f/0.7, f/1.4 two times more than f/1.0 and so forth.

F/No. and Background 

In order to blur the background of an main subject to create special effect, a larger aperture must be used such as f/2.8, f/2, F/1.4 or smaller f/number. The larger the aperture, the degree of blur is larger. If you want a clearer background select a smaller aperture such as f/11, f/16, f/22 or larger f/number.

Larger Aperture and Shutter Speed

The larger the aperture, the faster the shutter speed one can use to capture fast action activities or subject (e.g. a racing car)