Production: The Basics of Composition
Honing your composition skills is only a matter of practice. However, there are some conventions that you can try out as you discover your own personal tastes.
1. Rule of Thirds
Imagine an empty frame. Divide this frame using a tic tac toe pattern to get nine squares. This is the basis for the rule of thirds. This convention states that these lines should be approximately where you separate elements of your frame. Begin with a medium shot of a person. You can place the person in the center of the frame if you want to bore yourself. Instead, attempt to place them on either side of the frame. The lack of symmetry is more relaxing due to the reduced sense of rigidness. But, now you have emptiness on the other side of the frame. Try to fill it in by adding either a background or foreground element. This can be a piece of the person's shoulder or a table with a lamp on it. Anything to help balance out the frame.
In the example above, we will assume that you have put the person on the left hand side of the frame. If this is the case, you should have the person look towards the right of the frame (or their left). It is human nature to follow a person's eyes. Keep the eyeline moving into the frame rather than shooting off the other edge. If you had decided to make this shot an over the shoulder shot, then the eyeline would be going in the right direction anyway.
3. Head Room
Going back to the rule of thirds, we will now concentrate on the horizontal lines. Part of this idea is that the human eye is naturally drawn to a space approximately 2/3 up the frame. Try setting up your shot so that the characters eyes are right around that line. A lot of the time this will naturally give you the right amount of space between the top of the person's head to the top of the frame. However, everyone has their own opinion as to how much space is appropriate. Some like to cut off a bit of the person's hair, others prefer plenty of room. Finding your preference is up to you.
4. Leading Lines
Though you are filming a three dimensional scene, film (for the most part) is a two dimensional medium. This is the theory behind leading lines. Imagine a path in a garden. If you photograph it, this is an element that the viewers eyes will naturally follow in order to get a sense of depth. Use this attraction to lead the viewers eyes to key elements of your frame. Remember to also consider the rule of thirds here. Though you can still balance a photo if you arrange the path vertically or horizontally, a diagonal orientation will maximize the strength of your frame.
There are many rules and conventions to help train beginners in composition. However, ultimately it is all a matter of taste.