All movies and TV employ visual effects for that extra zing, but science fiction and other speculative genres rely on them to a greater degree. To believably portray alien planets and futuristic technology, filmmakers needed to create imagery unlike anything seen in the everyday world. VFX artists employed plenty of tried-and-true techniques: rotoscoping to create lightsaber glow, using miniatures and matte glass paintings to add aliens and spaceships into shots. One technique, though, built upon innovations of the past and created something new, and in doing so, helped define the aesthetic of science fiction as we know it today.
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What Is Slit-Scan Photography?
The technique of slit-scan photography dates back to the early days of the camera in the 1840s. Slit-scan photography refers to a technique in which a screen with a slit is placed between the camera lens and the subject of the photograph, and the slit moves from one end to the other over the course of a long exposure time. This resulted in wide-range shots.
Slit-scan’s earliest uses were in panoramic photography, but it was discovered that if the subject moves during the exposure, it results in distortions. Photographers began to play experiment to see what effects they could achieve. One example is shown above. This top-to-bottom slit-scan depicts fingers typing on a keyboard. The long, stretched-looking fingers were achieved by the subject of the photograph moving their hands as the slit moved down the frame. Filmmakers began using slit-scan in animated film, but it wasn’t until the 1960s that it became commonplace in live-action — most prominently in science fiction.
2001: A Space Odyssey
Slit-scan wasn’t uncommon in filmmaking’s early days, but the technique was innovated and popularized in Stanley Kubrick’s 2001: A Space Odyssey. This 1968 movie was of the strangest and most influential science fiction movies of all time, in part due to its visual effects. It used slit-scan in a way that nobody had seen before, to create scenes unlike anything in our world — namely for the Star Gate scene, in which main character David Bowman takes a trip through the Star Gate amid flashing, colorful lights and blurry, bizarre images.
Douglas Trumbull, the VFX artist hired for Kubrick’s film, created his own spin on the slit-scan technique to engineer these visuals. He was inspired by Alfred Hitchcock’s Vertigo, which used slit-scan animation to create swirling effects. Trumbull’s setup involved placing a camera on a moveable platform in front of a screen with a four-foot slit. Behind this screen was a series of colored gel images, including landscapes, cityscapes, geometric patterns, and more.
When the camera began rolling, it would move back and forth on a dolly while the images moved left to right, resulting in the dizzying, distorted effect seen in the film. Following each exposure, the images would advance slightly, such that several takes in succession would create an animated effect when placed together. Through this painstaking process, Trumbull created an otherworldly, futuristic feeling that captures the sensation of falling rapidly through space and time.
Other Uses In Sci-Fi Film & TV
Though 2001: A Space Odyssey brought the technique into the realm of sci-fi film, its use didn’t end there. Slit-scan VFX were used to create the iconic time vortex effect in the Third and Fourth Doctor’s eras of Doctor Who. The show’s artists used the technique to create trippy, outer-space-reminiscent visuals, showing the TARDIS as if it were falling through a wormhole.
Additionally, slit-scan was used in Star Trek: The Next Generation to create the “stretching” of the Enterprise as it jumped to warp speed. Consider how, when taking a panoramic photo with a modern cell phone camera, an object that is moved as the camera moves will appear stretched and distorted in the final image. This is similar to the slit-scan technique used to warp objects on film. The speed at which the image moves behind the slit can change the way the camera captures that image, allowing artists to distort the subject of a shot in just the right way.
How This Technique Impacts Modern Media
Considering the complex process by which Douglas Trumbull created the Star Gate in 2001, it should come as no surprise that slit-scan VFX are incredibly time-consuming and expensive to produce. As such, they are less common nowadays, but even the CGI artists of modern film use them as inspiration.
One need only look at Doctor Who to see the evidence. Though title sequence has undergone dozens of reiterations since 1974, that image of the time vortex has stuck. In the modern series, nearly all versions of the title sequence show dizzying colors and patterns representing the time vortex — though these were created with computers rather than slit-scan, the 1974 titles have made a huge impact. Similarly, although Starfleet’s ships now jump to lightspeed with the aid of CGI, it was slit scan photography that gave us the iconic image of the jump itself.
Although the specific processes employed in the past may not be used today, the distinct visual style that they created has remained in the hearts and minds of modern directors and producers. Wormholes look the way they do because of Space Odyssey and Doctor Who. Space-time anomalies cause people and objects to warp and distort in specific ways, because that’s what slit-scan photography allowed. Whether we realize it or not, we can see echoes of early VFX innovations in media today, baked into the aesthetic of what we consider classic science fiction.
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