Filmmakers push technology in certain directions, but technology pushes back at us, too. A breakthrough in one area can hold us back in another; a technology that makes one style of filmmaking easier can impede another. And sometimes, what was seen as a breakthrough with hindsight looks merely like a shift in convention.
In the heyday of movies in the 1940s, a cinematographic breakthrough was proclaimed: deep focus. Most famously pioneered by cinematographer Greg Toland in Orson Welles’ Citizen Kane, deep focus meant everything on the film set could be in focus at once. No longer did the filmmaker have to decide what was in focus and what was not. Everything was clear and sharp for the eye to discover. Some critics saw this as liberating the audience; rather than being controlled and directed, the viewer was free to make his or her own connections.
Deep focus (or deep depth of field, as we would call it today) was dependent on innovations in technology. Faster filmstock and powerful carbon arc lamps enabled Toland to shoot between f8 and f16 using (mostly) wide-angle lenses. A couple of years earlier none of this would have been possible.