Definition
The rule of thirds is to place the characters, important objects, or any other key element on imaginary lines that divide the image into equal parts. These lines must be placed in the third horizontal and vertical. They are called the lines of force and their intersections of the strong points.
How does it work ?
The diagram below illustrates this rule. We find two horizontal lines that divide the image into three equal parts. It is the same with the vertical lines. The four intersection points are represented by red circles.
By placing important elements at the center of an image, we created a print static and banal. The objective of the rule of thirds is to boost its framing, make it more alive. For this, it is necessary to so place the important elements (characters, object, horizon, etc.) on the lines of force, or better yet, on the strong points (the intersection points) of the image. The eye rests naturally on these strengths to understand what they are watching.
In view of the importance of these strengths, it is better not to put items to minors which would have the effect of sapping the meaning of your image, of your plan. Similarly, it is necessary to avoid to place two important elements on the same line of force. This would tend to weaken each other.
Examples
Here are a few examples that illustrate how to use the rule of thirds to the cinema and its impact on the image, the feeling of the viewer.
This image, taken from the movie the motorcycle Diaries by Walter Salles is very rich from the point of view of the rule of thirds because it illustrates both how to frame a landscape, but also how to situate the characters in the frame.
For a landscape with sky, the ideal composition will be based on cutting at one-third to two-thirds of the image. In the example above, the horizon line is located on the horizontal line high of the image. This has the effect of putting before the desert, its vastness. If the director had wanted to give pride of place to the sky, to support the heat of the place, for example, it would have located the horizon on the horizontal line low in order to have a proportion of two thirds for the sky and one-third for the desert.
In terms of characters, they are both placed on the vertical lines. The main character, Che, played by Gael García Bernal is advanced, and therefore valued compared to his sidekick. More importantly, his eye goes to the left. As it is located on the vertical line on the right, this has the effect of enhancing the eyes, by giving him more space, more depth.
For a large plan, the head of the actor must be placed on one of the strong points. The look will be enhanced if the eyes are located on the upper horizontal line.
In this example, from the film The lord of the rings – The two towers, Peter Jackson, all these rules are enforced to the letter. The two eyes of the character are on the upper line is the one of them is exactly on one of the points of intersection. In addition to the face, even the stick held by the character is located on a guideline. This gives him an aura extra. The object becomes inseparable from the character, is used to represent it.
To go further
Remember to finish that this rule-of-thirds is not born with cinema or photography. It has origins much more remote. We owe it to a roman architect.
It had put in place the golden rule in order that his buildings have the proportions perfectly harmonious. It is about putting in place an allocation of space which makes equal the ratio between the smallest and the largest part of the image to the ratio between the large part and the image in its entirety. This golden ratio is exactly equal to 1.618. This theory may seem somewhat complex… Yet, this is simply a further explanation of a mathematical principle used for the rule-of-thirds and his famous imaginary lines.