A lot of people keep hearing about depth of field, but they don’t really understand what it refers to. Basically the amount of the photo that’s in or out of focus front of or behind the subject is known as depth of field. You actually have the choice of what you want to be in focus and out of focus.
There are several ways that you can alter the depth. One of them is by setting the aperture on your digital camera. The smaller the aperture is, the larger the number of the f stop is. This means there’s less light getting into the camera and the depth of field will be greater, meaning more of the image will be in focus. For example, if the f stop is set at f/22, the whole image should be in sharp focus. If you set the aperture to f/2.8, then the only part of the image in focus will be the actual focus point.
This means if your aperture is at f/2.8 and you take a close-up shot of a person and focus on their mouth, their eyes will be out of focus. Taking the photo at f/8 would allow you to focus on the whole face and get a soft background. If you take the same photo at f/22, then the whole face and the background will all be in focus.