Deep focus is a cinematographic technique that allows objects or people to appear in focus on various planes of a shot. Simply, it means that things in the foreground and the background are in focus. It does this by using a large depth of field, which can be created using bright lights, a narrow lens aperture and by using a wide angle rather than a long lens. Deep focus can also be achieved through image trickery and manipulation if so required. It is the opposite of shallow focus, whereby only what is in the immediate foreground is in focus.
Although not invented by, Orson Welles and his cinematographer Gregg Toland have been widely accredited with popularising the technique. Other auteurs such as Jean Renoir, Hou Hsao-Hsien and Abbas Kiarostami are also renowned for using deep focus in much of their work. Some like to use deep focus purely as a stylistic choice, although some employ it as they believe it gives a more accurate representation of reality. After all, when looking at something in real life, you can choose how far to focus, whether to look at something in the foreground or the background. Deep focus helps to give that level of choice.
One could go on for hours about the intricacies of focal length, light gauges and so on (well I couldn’t, but some could) when discussing deep focus, but the best way to understand what it means is to look at some examples.
Here, in Jean Renoir’s Le Règle de Jeu (The Rules of the Game), you can clearly see that the couple through the doorway in the background are in focus as well as the two men in the foreground.
This scene from Citizen Kane is one of the best examples of deep focus and the uses it can have beyond the purely aesthetic. Here we can see three different planes all in focus. We have the mother in the foreground, the father a little further back in the doorway and then a young Charles Kane in the background outside viewed through the window. So just why is deep focus so instrumental in this scene and, consequently, the film as a whole? Well, we have Kane’s mother in focus signing the control of her son’s life away, and because of her positioning in the frame along with the character’s eyelines, we are drawn to this act. Normally, however, Kane playing outside would be out of focus, but by using deep focus, combined with the positioning of the window and the contrast in colours, we are also drawn to watching him play; the last few moments of him truly having child’s life. Having both these important events in focus links them semantically, providing the real crux of the story.
Deep focus is not used nearly as much as it was, especially in Hollywood films, primarily because the way films are made has changed. Lighting is lower to make working conditions more comfortable, shot length is shorter, multiple angles are now shot thanks to the ability to have more cameras on set, and you could argue that Hollywood films tend to focus less on the smaller details of filmmaking as the average moviegoer may well miss them. Still, the above example from Citizen Kane goes to show that deep focus can be an effective technique that can really enhance not just the look of a film but various other aspects too.