The heyday of the split focus diopter has mostly passed. The in-camera effect, created by attaching an additional piece of convex glass onto the lens of a camera, creates an impossibly deep field of focus, putting objects both near and far into focus, even in low light situations. The result is hyperreal and sometimes disorienting — in part because the human eye cannot achieve the same effect. But while the technique famously appeared in cinematic classics like “All The Presidents Men” and “Citizen Kane” — and reached its pinnacle in the ’70s and ’80s — it has mostly gone the way of so many other in-camera effects: traded for the ease of modern, high-quality post production.
One strong example of split focus is Brian De Palma‘s 1981 thriller “Blow Out.” The film stars John Travolta — still smoldering hot off the one-two punch of “Saturday Night Fever” and “Grease” — as an audio recordist working for low budget slasher films who accidentally records the real-life murder of a governor. “Blow Out” uses a total of 15 split diopter shots, most of them rather obvious, with little done to conceal the harsh dividing line the effect leaves. In most films, 15 such shots would be excessive. But De Palma utilizes the technique in concert with the films themes; “Blow Out” is about eavesdropping, spying and being spied upon. Throughout the film Travolta is often watching or listening to others from afar, and the split focus shots brings this eerie sensation to visual life. It’s a beautiful, if chilling, representation of the invasion of privacy and the intimacy felt by those doing the invading.
To see each of the 15 split focus diopter shots in “Blow Out” check out the video from Vashi Visuals. Got a favorite split focus shot? Weigh in with your thoughts in the comments.