characterized by a blurred line between the two planes in focus. The diopter gave the opportunity for spectacular deep focus-compositions that would have been impossible to achieve otherwise. 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. Use in modern films Starting in the 1980s, American cinema has developed a trend that film scholar David Bordwell calls intensified continuity. Bordwell claims that: The average length of each shot in a film has become shorter over the years Scenes are built up by closer framing More extreme focal lengths are used The scenes include an increased number of camera moves This trend has led to deep focus becoming less common in Hollywood movies. 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. In a contemporary Hollywood movie a dialogue scene may consist only of tight close-ups, with the master shot abandoned. If more than one plane in the image contains narrative information, filmmakers switch focus ("rack focusing") instead of keeping both focal planes sharp. In addition, modern sets tend to have less lighting for more comfortable working conditions, and use of deep focus tends to require more light. The development of intensified continuity may be due to directors' desire to capture the action or dialogue from many different angles and views. Getting these shots is called coverage. The U.S. film critic Dave Kehr explains it this way: If there is a single word that sums up the difference between filmmaking at the middle of the 20th century and the filmmaking of today, it is "coverage". Derived from television, it refers to the increasingly common practice of using multiple cameras for a scene (just as television would cover a football game). To stage a whole scene in one shot is no longer common. Director Steven Soderbergh claims: That kind of staging is a lost art, which is too bad. The reason they no longer work that way is because it means making choices, real choices, and sticking to them. (...) That's not what people do now. They want all the options they can get in the editing room. An extreme case of filming in one-shot is the feature-length