Please refer to my first post on Internal vs. External Theory of Three Dimensional Film Composition.
To clarify the difference between the two disparate theories, let us turn to the live stage play. The concept of a fourth wall within all forms of storytelling is best illustrated here. The fourth wall refers to the invisible barrier between the audience and the actors. All fiction is dependent, to a degree, on the suspension of disbelief. While the audience knows that the events they witness are fake, this realization is pushed to the back of their minds. Address or involve the audience, and the collective attention of the audience is directed back upon itself. This makes it impossible to suppress the aforementioned realization. As a result, the suspension of disbelief is destroyed.
The audience must be able to feel like an unnoticed or invisible observer to the events of the narrative. A “fly on the wall”, so to speak. There are times when violations of the fourth wall can be effective. Take the Glass Menagerie for example. One of the principal characters addresses the audience directly to double as narrator. Such examples are rare. It is generally advised to leave the fourth wall as an absolute.
So it is with the use of external theory. External theory always breaks the fourth wall. External theory, like any other method of breaking the fourth wall, is best used sparingly, if at all. I would recommend that all directors make a habit of avoiding external theory as though their careers depended upon it, for well it may. Even though the actors may not be addressing the audience, they or the props are approaching the audience in a direct manner when external theory is applied.
Instead of pointing an object straight at the center of the camera, throw the object a little off center. Remember that diagonal lines generally draw interest in the traditional two dimensions. So it is in the third. Remember the rule of thirds. If looking down at a skyscraper, make the bottom appear to align with the lower left-hand intersection and the top with the upper right or from the lower right intersection to the upper right edge This way, internal theory comes into play.
Also, try to focus on layers of activities and objects as opposed to a single object performing a single action. Rather than focusing on a single train coming downstage along the track into a station, place the camera close to a perpendicular angle with the principal train in the foreground so that the action of all the busy trains runs back and forth in layers of depth.
Ever notice how a cubicle seems so tiny, yet the room containing the cubes is so vast that the cubicles seem to go on forever? Use 3D to your advantage to contrast the spaces. The third dimension can do so much more than make the audience jump. Overuse that one aspect and it becomes old hat very quick. 3D can assist the filmmaker in making the overall tone of a scene feel closed in, without escape, and very panicky. Or it can be used to create a sense of unbridled freedom and open space. Filmmakers already employ techniques to create these feelings, 3D can enhance them. Just don’t throw every storytelling concept out the window as soon as someone mentions 3D. Many of the same principles of storytelling, design, and composition still apply. They just have one more aspect to play with, that’s all.
The three dimensional screen is more akin to the stage than anything that came before. Preserve the fourth wall. The moving view-master of three dimensional film is a playground of limitless potential. Many directors approach 3D as though it were a loathsome, constraining thing. It is exactly the opposite. It is freeing if you work with it rather than against it. 3D is the new color, the new talkie. Get used to it. Apply internal theory.