Basics: Aperture in Photography

Playing with Aperture by sonicwalker

The opening of the lens diaphragm inside a lens is commonly known as Aperture. This opening regulates the amount of light that is passed through onto the film or the image sensor.

The size of an aperture in a lens for a point-and-shoot digital camera is normally fixed. However, it is very useful to know about aperture even if you’re using a compact camera. Prosumer, SLR and Digital SLR cameras often allow the photographer to adjust the aperture. Aperture size is usually measured in terms F-stops or F/number. The smaller the F-stop, the larger the opening of the lens (i.e. more light is captured into the photo).If a lens has a low F-stop (F/1.8), it is often called a “fast lens” that can allow more light in a low light environment.

Increasing the F-stop by 1 (F/2.8 to F/4) will half the size of the opening in the lens and reduce the amount of light entering by half. Reducing the F-stop by 1 (F/4 to F2.8) will double the opening in the lens and also double the amount of light entering. To summarise, the smaller the F-stop, the bigger the opening of the lens. The larger the F-stop, the smaller the opening.

Depth of Field

Changing the aperture will not only affect the amount of light captured in your photos but it will also have an impact on the Depth of Field. Depth of field will affect the amount of a photograph that is in focus. The larger the Depth of Field, the more of your photograph will be in focus. The smaller (shallow) the Depth of Field, the less of your photography will be in focus.

Drip by noahbulgaria

The photo above demonstrates a small (shallow) Depth of Field where the cherries in the middle of the shot are in focus and the background of the image are blurred.

There are many more resources available from experts who can explain Aperture and Depth of Field much better than I can. Below are some of my favorite articles that are easily understood even by an amateur like me:

Aperture

1. Aperture on Wikipedia
2. MIR - What is an aperture?
3. Photoxels - What is….Aperture? (Great DoF explanation too)

Depth of Field

1. Depth of Field on Wikipedia
2. CambridgeInColor - Understanding Depth of Field in photography
3. Photoxels - Depth of Field

How did you learn about Aperture and DoF? Share your experiences with us in the comments!