By changing the aperture in the lens, you can make the resulting picture have more of the picture in focus from near to far, or you can limit the picture’s focus in one place.

• At ƒ1.8, the focus point will be much more defined with things in front of and behind the subject becoming softer looking further from the subject they are. This is a very nice way to bring attention to the subject.
• At ƒ22, the focus will seem to be sharp from very close to the camera to pretty much infinity. This is great for giving a sense of the place you shot the image, or for including many people in the image and keeping everyone clearly in focus.