Deep focus

Since the aperture of a camera determines how much light enters through the lens, achieving deep focus requires a bright scene or long exposure.

Filmmakers such as Akira Kurosawa, Stanley Kubrick, Kenji Mizoguchi, Orson Welles, Masahiro Shinoda, Akio Jissoji, Terry Gilliam, Jean Renoir, Jacques Tati, James Wong Howe and Gregg Toland all used deep focus as part of their signature style.

He elaborated in an analysis of how deep focus functions in a scene from Wyler's The Best Years of Our Lives: The action in the foreground is secondary, although interesting and peculiar enough to require our keen attention since it occupies a privileged place and surface on the screen.

Paradoxically, the true action, the one that constitutes at this precise moment a turning point in the story, develops almost clandestinely in a tiny rectangle at the back of the room—in the left corner of the screen....

This is because the size of the sensor or film gauge dictates what particular lens focal length would be used in order to achieve a desired viewing angle.

Because depth of field is a characteristic of lens focal length (in addition to aperture and focus distance setting), it is easier to achieve a deep-focus look with a smaller imaging sensor or film gauge.

Cinematographer Dion Beebe commented: We also decided that there were attributes of HD technology we liked and wanted to exploit, like the increased depth of field.

In the American New Wave, director Brian De Palma explored the possibilities of the split-focus diopter extensively, as did other '70s films such as Robert Wise's The Andromeda Strain and Star Trek: The Motion Picture.

Starting in the 1980s, American cinema has developed a trend that film scholar David Bordwell calls intensified continuity.

As mentioned in Bordwell's second point, master shots where two or more characters hold a conversation have gone out of fashion, lessening the need for deep focus.

The development of intensified continuity may be due to directors' desire to capture the action or dialogue from many different angles and views.