F.Stops and Aperture

Aperture: is the lens opening and controls how much light is passed through the lens.

F.Stop: are the numerical measurements of the Aperture.

As you can see in the diagram above the lower the number (i.e. F2) the larger the opening of the lens which allows MORE light in. On the flip side, the higher the number (i.e. F22) the smaller the opening which allows LESS light in.

So what's the big deal? Why is Aperture/F.stop important?

One of the important things the f.stop/aperture affects is the depth-of-field. The f.stop/aperture on the lens controls how much of the image is in focus in addition to the point you specifically focused on. For example, a lower (wide-open) aperture (i.e. F 2.8/F4) will produce an image where only the subject focused on is sharp, and the items in front of and behind the focus point are out of focus in varying degrees. A higher aperture (less opening in the lens - i.e. F11/F16 +) will produce images with more or all of the subject and surroundings in focus.

*Information from Judith Pisconeri and Light and Lens. www.pisconeri.com