How visual effects legend Hoyt Yeatman and tests being done for 1998’s ‘Mighty Joe Young’ led to the SFX 200T film stock.
By the mid-to-late 1990s, visual effects supervisor Hoyt Yeatman had won a VFX Oscar for The Abyss and had worked on several seminal visual effects projects at the studio he co-founded, Dream Quest Images.
His next project would be Mighty Joe Young, for Disney, where Rick Baker’s Cinovation Studios would be responsible for animatronic gorilla suits.
“The plan was to capture many scenes with suited performers against bluescreen, using real-time motion control, miniatures and forced perspective, with the camera actually moving in three-space,” Yeatman shared with befores & afters.
Disney then requested some tests be carried out to see if that shooting methodology would work. A simple test against bluescreen with one of Baker’s gorilla existing suits was devised. This is where Yeatman started noticing a problem.
“We shot our tests in VistaVision, which uses 35mm motion picture film, sideways, so that we had a much larger film negative,” recounts Yeatman. “Now, importantly, Mighty Joe is actually a dark redhead. He’s not actually a black gorilla. What we noticed in these tests was that, no matter what we did, we had this red fringe around some of the hair.”
Now, Yeatman was of course aware that compositing any character with hair was a tricky prospect. Visual effects artists and studios had dealt with that issue for decades, originally in the optical compositing world, and then via relatively new digital compositing techniques. Remember, at this time, films were still shot on film. Digital compositing (and CGI) was only in its infancy. While Mighty Joe Young (released in 1998) would go on to feature fully digital gorilla work, there were still many sequences realized with practical suits, all shot on film.
The specific problem Yeatman and his team were encountering occurred when they attempted to pull mattes off the bluescreen test plates. There were, notes Yeatman, artifacts visible on the edges of the matte producing a magenta edge.
It wasn’t necessarily a new problem, but it was one that stood out in the bluescreen gorilla test footage. “Previously, there were ways in film compositing that studios like ILM, Apogee, Boss Film and Dream Quest used to deal with these deficiencies, ie., where you had a particular fringe,” says Yeatman. “One way was to change the edge of the matte. But in the case of a hairy gorilla, if we started to do that we’d definitely compromise the look of the holdout and the look of the composite because we were encroaching on very fine hairs.”
“To explain that further,” adds Yeatman, “you typically back-light a hairy character like that to photographically make them look good. Doing it that way produced an image that included these translucent hair fibers. In our separations, the red layer, or the cyan layer, which represents the red layer, that was the one that was out of whack with the rest of the other two layers. It accentuated those problems, because the thin hairs of the gorilla back-lit would be this deep red, which made the cyan layer travel out. So, it was probably the subject and the color of the subject that really emphasized the problem. If you had been shooting a gray spaceship or something like that, you wouldn’t necessarily have seen this problem so much. But with a fully big gorilla, up close in VistaVision, you could really see what was going on.”
More tests carried out at Dream Quest further highlighted the issue and left Yeatman unsure of the cause. Luckily, the studio at that time still retained an in-house film processing lab to deal with separations for bluescreen compositing and matting. “Because of that, we had a little area that was our control area, where we had different instruments that we could monitor the film during the processing.”
One of these instruments was a sensitometer, explains Yeatman. “A sensitometer is a device that has a light in it with precision bars and gray scales. There are no lenses involved. You put the film in and expose it. You don’t have any chromatic aberrations or any problems through an optical process. It let us look at the sensitization of the film stock—Kodak 5248 was the film we were normally using back then. Looking under microscopes, we could see that we had this fringe.”
What Yeatman had uncovered was that the three emulsion layers of the film were not lining up with one another. The cyan level, the red record, was offset. He reached out to Kodak about the issue. “I was able to have a dialogue with Kodak. They brought out two young film designers and I showed them what was going on. And they said, ‘You know what? That is a problem.’ They recognized that the problem made things less sharp. You’re not getting the three colors to line up. So they said, ‘Let’s work on it.’”
Kodak then took on the challenge of creating a whole new film stock where the three emulsion layers lined up more precisely, with Yeatman advising them from an end-user standpoint. “Within a six month period, we had this experimental film we were dragging out onto set when we were shooting. It was amazing. It was technically the sharpest film that they had, because as one might imagine, if all three layers line up properly, then you get really distinct images.”
The result, with this new film stock, was that the fringing issue had disappeared, something Yeatman believes Kodak possibly achieved by altering the anti-halation backing, right below the cyan layer of the film, and limiting the way that the three separate color layers of the film might shift slightly in processing. “Ultimately, we were able to get Mighty Joe Young to be matted properly without matte lines,” says Yeatman. “It looked fantastic.”
The new film stock became Kodak SFX 200T color negative film. This is how Kodak described the film in a technical data sheet:
SFX 200T Film is optimized for traveling matte shots, so foreground action photographed against a blue or green screen can be separated more cleanly from the background when it’s scanned into the digital format. In complex composite shots, this film can save time in postproduction.
At EI 200, this film intercuts seamlessly with other Kodak Color Negative Films used to record live action footage. Even visually astute audiences will find it difficult to determine where visual effects begin. The filmmaker’s vision can be made real with fewer compromises.
Kodak SFX 200T Color Negative Film is a medium speed, tungsten-balanced color negative camera product with microfine grain, unprecedented sharpness, and high resolving power. It features wide exposure latitude and accurate tone reproduction.
At the 72nd Academy of Motion Picture Arts and Sciences Scientific and Technical Awards, Yeatman and John C. Brewer of the Eastman Kodak Company received a Technical Achievement Award (Academy Certificate) related to Kodak SFX 200T. Here’s the full citation:
For the identification and diagnosis leading to the elimination of the “red fringe” artifact in traveling matte composite photography. The elimination of the “red fringe” artifact in traveling matte composite photography obviates expensive additional computerized image processing thus reducing the time involved in producing a seamless and convincing composite shot.
A number of films shot with SFX 200T for visual effects sequences. Then, in 2004, Kodak introduced its new KODAK VISION2 200T color negative film, which effectively replaced SFX 200T. Soon, too, more and more productions would be filming on digital video, rather than on film stock. For Yeatman, despite having worked for so long in celluloid, and despite making a major contribution to the medium with SFX 200T, he recognized that a shift to digital was inevitable, and welcomed.
“I mean, the process of working completely in film was a nightmare. It was so physical. In those days you really had no interaction and no visual feedback. You had to use your imagination about what it might finally look like. It’s something I don’t look back on with many fond memories. But, with SFX 200T, at the time, because of what it was and how it was used, it became very popular. Everyone doing visual effects at that time began shooting on it.”
