Deep beneath the sea, a ghostly-white giant octopus clings to spherical globe of a submarine carrying scientists. A huge, majestic jellyfish-like creature swims past. Thousands of tiny shrimp, surviving inexplicably around thermal vents hot enough to melt the submarine itself, play in the background. Indeed, these are creatures one might expect to see in a James Cameron film, except this is reality—at thousands of feet below the surface of the ocean.

"It's not a location—it's a world," says Director of Photography Vince Pace of the sites visited in Cameron's new 3D IMAX film, Aliens of the Deep (Buena Vista). The movie takes audiences to thermal vents beneath the Atlantic and Pacific oceans, where the oddest and most rarely seen animals thrive. Sea creatures here have no skin pigmentation because no light ever penetrates these depths.

For both Aliens of the Deep and Cameron's previous IMAX film, Ghosts of the Abyss, the director captured images of the underwater world in 3D with custom-built HD cameras. His Reality Camera System (RCS-1) was designed in a joint venture between Cameron and Pace using pairs of specially modified Sony HDW-F950 CineAlta cameras.

The idea for Aliens of the Deep came about while Cameron and Pace were filming another project in May 2002, Expedition Bismarck for The Discovery Channel. The team was accompanying a Russian crew that, after exploring the Bismarck wreck, was to make further visits to the mid-Atlantic ridge, after dropping off Cameron's gang. "We were supposed to all get off in the Azores, but I asked Vince and one of our engineers, Ronnie Alum, to stay on board for a month at one of these sites," the director says. Adds Pace, "When Jim asked if I'd like to shoot the thermal vents, I said, 'Man, now there's a 3D subject for you.'"

The pair made four or five dives and captured about 11 minutes of spectacular footage using the 3D RCS-1 camera system. "Even though Bismarck was a 2D show, we shot the underwater sequences in 3D," Pace explains. On Ghosts of the Abyss, the camera's lenses and optical blocks were set in a specially built waterproof housing (designed by Cameron's brother, Mike) attached to the exterior of the Russian Mir submersible; the system used a high-pressure penetrator to connect to the processor and recorder in the sub's interior. For Aliens, the new RCS-1 system placed each processor in a separate high-pressure housing on the exterior of the sub.

As mentioned, the camera system is based on a pair of modified Sony F950 HD cameras, which capture information at 4:2:2 HDCAM. There are two adjustable parameters for 3D cinematography: convergence angle (the angle between the axes of the two lenses) and interocular distance (the lateral distance between the two lens axes). "Sony made us a repackaged optical block, which was shaved down to allow the narrow interocular required for good 3D," explains Pace. On RCS-1, the interocular distance is fixed at 2.5 inches, the distance between the average pair of human eyes.

While on Ghosts, the system utilized a specially designed matched pair of Panavision Primo Digital 7mm lenses, Cameron went with a different lens system for Aliens. "We wanted macro capability. We wanted to be able to zoom in on interesting animals," he says. "We asked Canon, Angenieux and Fujinon to build special lenses for us that could use that narrow interocular distance, because off-the-shelf lenses wouldn't work," explains Pace. Ultimately, it was Fujinon that provided pairs of 5.5mm-55mm, 10:1 zoom lenses, specially designed to allow for the close interocular requirement. Pace then developed a synchronized zoom, focus and iris control, which adjusts the lens settings using the lenses' individual controls together, as opposed to a master/slave system, notes Pace.

The team began using the new lens system on the Bismarck expedition, but they soon came upon a peculiarity that required additional fine-tuning. "The problem is that these cameras are placed in the underwater housing, shooting through a dome optical port made of 3.5-inch optical acrylic," explains Cameron. "That's the kind of stuff that drives cinematographers crazy. It's like a big fat plastic lens, which tends to introduce issues of chromatic aberration at the edges of the field, barrel distortion and spherical distortion. The reason is that you don't have a single lens aimed through the center axis of the dome—each lens is aimed slightly to the left or right of center."

The solution lay in a special diopter conceived by Cameron and Pace (prototyped at Pace Technologies) that was placed between the lenses and the dome port. "We actually discovered that issue in 2001, and Vince spent six months developing this adaptive optic," says Cameron. "We then found that the prime lens solution didn't work with macro and zoom lenses, so the diopter had to be re-created, re-ground to integrate the Fujinon lenses." The finished diopter was shipped to the team at the Azores, after the Bismarck mission, and incorporated into the camera system. It was tested in the plunge pool aboard the Russian ship. "It's where their crew relaxes—it's 40 degrees! It's very hearty and Russian."

About a year later, Cameron picked up the reins again on the project, deciding to return to the Atlantic Ocean sites as well as additional sites in the Pacific. "He said, 'We're shaping a show around this footage we shot. Do you want to head out there and do this right?'" recalls Pace. "We revisited all of the same sites. Jim could have cut the production cost in half by assuming the viewer wouldn't know the difference, but he wanted to be thorough."

Besides his camera crew (co-directed by Cinematographer Steve Quale, who had worked with Cameron on second unit on Titanic), Cameron invited members of the scientific community to join the expedition. "Usually it's the film crew that's tagging along on a scientific expedition," notes the director. "This time, we set up the trip and invited members of the National Science Foundation and U.C. Santa Barbara, as well as astrobiologists from the Jet Propulsion Laboratory and the Johnson Space Center to join us. That was really the heart and soul of the expedition."

For the new expeditions, Cameron returned with a pair of Russian Mir subs, which could dive to a depth of 6,000 meters, as well as a pair of acrylic-domed "rovers." Those rovers, while smaller—accommodating a crew of just two and capable of dives only as deep as 1,000 meters—allowed a maneuverability not possible with the large Mir submersibles. "The Mirs are so huge and massive and sluggish in their movement," says Pace. "The rover is very quick and articulate, and it can fly anywhere it wants. The rover also offers a tremendous field of view." The Mir, because of its higher pressure depth rating, has only a seven-inch window (four-inch window for the passengers and camera, and a seven-inch window for the pilot).

Five RCS-1 camera systems were brought on the mission, though the usual dive setup, with two Mirs and two rovers, was to have a camera system mounted on one of each. "One of the pair, containing a pilot and one of the scientists, would act as a 'picture ship,' while the other, with a pilot and Jim or myself operating the camera, would be the 'camera ship.'" The system enabled Cameron to capture reactions by the scientists within their ship or view the ship interacting with the underwater environment.

The cameras, as mentioned, were placed inside housings built to withstand the high water pressure. "Our housings are designed for 6,000 meters, which has an ambient pressure of around 8,000 psi, or about four tons per square inch," says Cameron. Pace explains, "The reason they're designed for that depth is that there's a real chance of the housings imploding, and the force of that implosion could compromise the submersible it's attached to. So we treat the package that's holding the camera as if it were holding a human life."

Mike Cameron and Ron Allum designed a specialized pan/tilt system to operate the cameras. "Deep ocean pan and tilt systems don't really exist," says Cameron. "They have ones for scientific photography, but they're incredibly jerky. They have no ramping, no ability to deftly perform the move. They just kind of jerk from position to position. We decided to build a system that's essentially an underwater motion control system." The pan/tilt system also integrated the lighting system, which comprised about 22 1,200 watt HMI instruments from Deep Sea Power and Light.

"The camera pans, and the light goes with it. One of the big problems with a camera panning all over the place in a dark environment [is lighting]. It required a whole second operator to keep the light moving with it. The Mirs, the deep rovers, didn't have a seat available for that second operator, so we made it an automated system," designed by Ron Alum. "The lighting to enable Jim to capture the footage in a very cinematic style is a critical thing here," notes Pace. "Jim's trying to choreograph both the sub position and the angle of the lighting, and I'm trying to fill light his frontal view or key light the scene, depending which sub I am in."

Additional photography was captured by a Remote Operated Vehicle (ROV), a small robotic camera vehicle. A pair of the diminutive ROVs, dubbed "Jake" and Ellwood," designed by Mike Cameron, were used on Ghosts of the Abyss to penetrate wreckage inaccessible to larger submersibles; only Jake came along for Aliens, piloted by either of the Cameron brothers. "It sends a single NTSC signal [i.e., only single camera] back to the submersible through a fiber optic line, where it's recorded on a DVCAM recorder," describes Pace.

In one scene in the film, Jake is enveloped by a school of deep ocean shrimp. "The Russians were always bringing up scientific samples of various sea life, and they brought up some of those shrimp," Pace recalls. "They actually cooked some of them up and asked if I wanted to try one." And how did they taste? "Like a mouthful of metal shavings."

Though it was possible, in some instances, to capture the scientists at depth using cameras on adjacent subs, some of the reaction shots had to be re-created later in the studio. "We actually placed two or three Toshiba three-chip lipstick cameras in each submersible to act as witness cameras," says Cameron. The lipstick cameras recorded to DVCAM decks inside the subs. The resultant footage was not used in the finished film; rather, it was used to show the scientists their live reactions during the filming of the re-creations in sub mockups at Panavision's Woodland Hills stage or onboard a parked Mir.

"We took that lipstick camera footage, edited it down and created a narrative spine. Then, when we'd re-create those moments with the actual scientists, we'd show them the video. In a sense, it's not really acting, like doing lines from a script; it's just re-creating something they already did. Some people would say [that re-creation] crosses the line in a documentary, but IMAX films, historically, inhabit a strange area in the documentary field."

In addition to the 3D cinematography shot using the Cameron/Pace camera system, the film contains some fine 3D stop-motion scenery that was photographed under the supervision of Co-Director Steve Quale. "We actually had two camera systems for the stop-motion work," Quale explains. "One system featured a pair of Canon PowerShot S400 Digital ELPH still cameras—one of the cameras was mounted upside down to help us reduce the interocular distance. The shutters were hard wired together, allowing for simultaneous release. The drawback to that system was that the cameras don't have manual exposure controls, so we had to put ridiculous amounts of ND filters in front of the lenses to allow the camera to shoot long exposures and get motion blur." That system was used by Larry Herbst to shoot footage of New York City.

A second, more advanced digital stereo camera system that consisted of two Nikon D100 cameras was used for much of the remainder of time-lapse footage. "Those cameras were so large that we had to use a custom-built beam-splitter rig," Quale explains. A beam splitter uses a half-silvered mirror to transmit half of the light data through the mirror and reflect the other half to another camera. This process allows light to be sent to two different cameras that may be too large to sit close together in the same 3D rig. "The Nikon rig allowed us total manual control, interchangeable lenses and the ability to shoot at a faster frame rate of two seconds per frame."

The underwater 3D footage was treated to one last step before the film was completed. "We found that the tremendous electronic fields that are generated by equipment in the submersibles introduced a great deal of noise in the images as they were being recorded," says Pace. "We'd have a fantastic dive, with crystal clear images, and then we'd find the footage was compromised with signal noise. It was like a gremlin that wouldn't go away."

Cameron decided to allow Burbank-based Lowry Digital to attempt cleanup. "We sent them a few shots with some interference and said, 'Let's see if these guys can smooth that out,'" recalls Cameron. "We were so impressed by the results, we eventually had them process the entire movie. We did a complete, end-to-end test, and filmed it out to IMAX. Their system essentially doubled our resolution." Adds Pace, "Their system was even able to tell the difference between digital noise and heat shimmer from the underwater vents."

Cameron and Pace intend to continue their digital 3D adventures with a new feature film and a new camera system. Currently in development for Cameron's Battle Angel, based on Japanese manga graphic novels, is the RCS-2 camera system. Incorporating Sony HDW-F950 CineAlta cameras with 4:4:4 resolution, the system will offer improvements such as adjustable interocular distance, fiber optic recording and control, and a shorter zoom lens system, again designed by Fujinon. The RCS-2 will also come in a beam-splitter version to enable both hyper-stereo and macro shots.

Cameron adds, "I'd be happy if I never touch film again. Filmmaking is not about film, it's not about sprockets. It's about ideas, it's about images, it's about imagination." He looks forward to the day when motion pictures are routinely presented using digital projection, making 3D movies accessible to everyone at their local theater. "We're in new territory, but I like new territory. New territory is the most fun place to be."