Unless your subject is perfectly symmetrical, the screen should never be divided exactly in half by strong horizontal or vertical lines. Instead, it should be divided approximately into thirds. For example, the horizon (if you're shooting a corn field) should be either a third of the way from the bottom of the screen or a third of the way from the top. With the exception of titles, composition should not be perfectly symetrical, but should rather balance positive and negative (filled and empty) space.Intelligent use of composition can be used to draw the viewer's eye to important parts of the picture.