Depth-of-field is the term for the range of things in a shot that are in focus. Manipulating depth-of-field is one of the main techniques that professionals use to make their films look, well, professional.

As mentioned earlier in the lesson, by setting up a scene so only certain elements are in focus, filmmakers can direct the viewer's attention precisely.

From a practical standpoint, there are three ways to increase or decrease the depth-of-field in a given shot.

1) Focal Length

Using a telephoto lens settings limits the number of things in focus. That is, depth of field is decreased. Conversely,  wide angle lenses increase depth of field.

In the shot at the right, a telephoto lens is used to decrease the depth of field and ensure the house goes slightly out of focus.