WPGphoto.com - Aperture tutorial

Tutorials

Aperture
Depth of field
Exposure
Field of View primer
Home made ring flash
Special Flash Effects

Tutorials are given a difficulty rating out of five stars(*). Five stars being the hardest to master.

Aperture tutorial -Article and photos by Dan H.
What it is and how and when to use it.

Difficulty level - ***
Camera-Any camera with aperture priority or manual control.

Intro
The aperture is a mechanism in the lens (or the camera itself sometimes) which controls the amount of light which passes through the lens to the film or sensor when the shutter opens.

Aperture sizes

Standard aperture settings on most cameras range from f/2, f/2.8, f4, f/5.6, f/8, f/11 and f/16.
Each increment represents a halving or doubling of the amount of light that will pass through the lens during exposure.The larger the f/stop number the less light will pass though the lens. For example: f/4 lets more light in than f/8.

This example shows the difference in openings of the aperture. The smaller the # the more light that is allowed to pass through.

Aperture and it's effect on depth of field

Another important aspect to aperture is that it also controls the depth of field or DOF.
The smaller the aperture setting, the less depth of field and thusly the less area of acceptable focus.

Try this yourself.

In this example, on the left, only the 2 is clearly in focus but not much else. On the right almost everything from the 1 to the 4 are in clear focus.

In other words, if you want more of the image to be in focus, use a higher number of f/stop.
If you want a very shallow depth of field, use a smaller number f/stop.