Though art can be made in many forms, there are some concepts that hold true in every situation. Because of this, it can be very helpful to know the principles behind aesthetically pleasing framing so that every one of your shots tells the story you want it to.
Behind every great shot is a great composition. Without a pleasing composition, shots tend to look amateur and lifeless. So even if you're not planning on being the next Ansel Adams, it's still a good idea to know about such important concepts as leading lines, rack focusing, lead room, natural framing, and balance. By doing so, you can make sure that your shots stand out from the rest.
One of the best ways to direct a viewer's eye is through using Leading Lines. Leading lines are naturally occurring lines in a shot that point towards the subject in a shot. Leading lines can be either horizontal, vertical, diagonal, or curved. Horizontal lines like those found in Forrest Gump when Forrest finally stops running after years on the road, can show serenity and inactivity. On the other hand, vertical lines like those used in the Dark Knight can show strength and dignity. Since the subject is so small in this scene, the vertical lines of the tall buildings can also be very ominous. Also, diagonal lines can show action, imbalance, and insecurity as seen in this example from Snatch when a man is in real fear for his life and in this example from Forrest Gump in which the diagonal line makes a connection between Forrest and the politics of Washington D.C. - which is represented by the Washington Memorial. In a nutshell, leading lines are a powerful psychological way to direct a viewer's attention to an area of the screen while making an emotional statement about it as well.
Another very effective way of directing the focus of the viewer is by using a rack focus. A rack focus is a technique where one object in a scene starts in focus and gradually goes out of focus until another object in the shot is in focus instead. This example from X-Men Origins: Wolverine shows an effective use of a rack focus. In this scene, a boy is trying to hide a knife from his father. In order to make the audience aware of his knife, the scene starts in focus on the knife, then it transitions to being in focus on the father showing that he is unaware of the object in the boy's hand. An important purpose of a rack focus is to show the relationship of one item in a scene to the other item in the scene that comes into focus. In the same movie, a rare metal is found by a general which becomes the area of focus. To show how the metal relates to the people they are taking it from, the camera refocuses on their tribe. This rack focus helped connect the two events happening in the film.
Giving a subject lead room in your video is yet another way to keep your audience pleased with your shots. Lead room refers to the cushion of space in the frame that is needed for objects that are in action. That being said, if you are already utilizing the rule of thirds in your framing, having proper lead room won't be an issue. This is because if you've already used the rule to frame your subject in the right third of the frame and they walk left, you will at least 2/3rds of your frame left for lead room. This gives you plenty of real estate for errors in panning as well as helping the subject to not look like they are about to run into the edge of the frame. Even in interviews, giving subjects a two-third of the frame distance in front of the area they are looking at can help viewers feel at ease.
One of the most clever ways to direct your viewer's eyes is to use natural framing in your production. Objects such as trees like in this shot from Braveheart can help frame your subject and draw interest to it's area of the screen. Doorways and windows can also be used to naturally frame a subject. In this scene from Smokin' Aces, both men are naturally framed inside the mirrored circles that are on the wall behind them. This draws attention to both men and makes them feel more separate at the same time. All of these methods are great for framing your subject but with some creativity, any number of objects can be used as well.
Lastly, balance can be used to help your audience feel at ease about a shot. Balance refers to the way difference between the amount of objects on one side of the frame compared to the other. If you have a lot of items on one side of the screen like this underwater scene from the Life Aquatic, the scuba diver has been framed to one side of the shot without any object to balance his weight on the other side of the frame. This gives the scene more tension and helped the audience feel apprehension about the events that were about to unfold. On the other hand, if, like this scene from Little Miss Sunshine, you keep the objects on both sides of the screen balanced, you can give your video not only a formal appearance but also put your audience at ease.
Composition isn't merely a technical term - it's a concept that needs to be closely entwined in every clip that you shoot. Understanding how to artistically place elements in a frame using leading lines, rack focusing, lead room, natural framing, and balance, can help you to effectively direct an audience to the area you want them to see.