Talking About Focus

Movies use "focus" for effect. When an object on the screen is "in focus," the viewer can see the details of the object. When an object is "out of focus," the viewer cannot see the details of the object--a face will look like a blur, for example. When you are very tired, or when you rub your eyes very hard, your eyesight will go out of focus.

Look at this example. The valve (the red thing) is in focus; behind the valve is out of focus.

http://dragonballyee.com/archives/photos/2006/03Mar/0379/0379.jpg

"Deep focus" is when everything on the screen is in focus. Here is an example from "The Best Years of Our Lives."

http://en.wikipedia.org/wiki/Image:Best_Years_of_Our_Lives_01_bar.jpg

"Shallow focus" is when only the image in the foreground is in focus. Here is a short vocabulary.
Foreground: The object closest to the screen.
Middle ground: the objects in the middle of the screen.
Background: The objects far away.

Here is an example of shallow focus. Only the boy's face is in focus.

http://farm1.static.flickr.com/172/427807020_0ce14b8469.jpg

--A lot of movies change the focus in a scene for effect. For example, a lot of you have seen the movie "Lust, Caution." In the Mahjong game scenes, the women will often say mean things to one another. Many times, one woman will say something mean to another; right after that, the woman who just spoke will go "out of focus," and the woman who was just insulted will go "in focus."

"Rack focus" changes the focus from the foreground to the middle ground, or from the middle ground to the background, or from one person's face to another. Many movies will use "rack focus" when two people are talking. The person talking will be in focus, and the person listening will be out of focus. (Sometimes the person listening will be in focus, and the person talking out of focus.)

Here's an example of "rack focus." There is a camera looking through an airplane window. In the picture on the left, the focus is on the objects outside; the "rack focus" changes the focus to the airplane window glass (and now the objects outside are out of focus). In "rack focus," the focus will change from the outside to the window, and back again.

1. http://static.flickr.com/28/88771773_608200c950_o.jpg