The film sequences of The Cave were shot in 3-perf Super 35mm 2.35:1. Emery and Hunt wanted to use the widescreen format to frame two or three characters together in order to maximize coverage and foster character interaction. Emery wanted to avoid big crane moves and locked-off shots because he wanted to maintain a sense of constant motion. Given the emphasis on handheld camerawork, he chose two Arricam Lites (provided by Arri Munich) to make things as easy as possible for the operators.

Emery shot most of the picture on Kodak Vision2 500T 5218, but to give a prologue sequence set in the 1950s a grainier, lower-contrast look, he used Vision 500T 5279 and pushed it one stop. All of the processing was done at Kodak Labs Romania. “That lab is as good as any I have used in the world, maybe better,” says Emery. “[Lab manager] Cornelia Popa and telecine grader Alex Ciocan both went to great lengths for us and made my job as easy as it could have been.

“We had dailies transferred from neg to video, but I also had select shots printed at the lab just so I could keep track of printer lights,” continues Emery. “This is such a dark film I wanted to be sure I was printing at a reasonable level. If the dailies looked a little too dark, I’d get the shot printed, and if I was printing in the 40s I knew I was on track. It’s often hard to make accurate judgments with video dailies, because you don’t know whether it’s you or the grader whose work is too dark.”

Emery used Zeiss Ultra Primes, mainly because of their ability to stand up to flashlight beams being pointed directly into them. The 28mm, 40mm and 65mm lenses were his workhorses. “I’m not a fan of very long lenses because I think they separate people from their location. With wider lenses, you feel like you’re there with the character. Also, when you have the great sets we had, you want them to be a part of the film.”

Skiles chose a single lens for the HD material, a Fujinon HA13x4.5ERM EFP-style zoom, which was complemented by optics in the housing built for the HDC-F950 by Amphibico. Ron Hand, president of Amphibico, says the optical elements of the housings are designed to remove the diffraction factor of water. “It’s a whole series of steps and sags,” says Hand. “There are five elements of glass to achieve this. The aspheric element is made of coated optical acrylic, about 5-by-10 inches in its 16x9 configuration and fairly thick in places.” The result is that even when a camera is half submerged, there is no distortion to the image, and edges stay straight. The image was so clean that at one point, when editor Brian Berdan needed a POV for a character above the surface looking at the top of a cave, he cut in an underwater shot, and even though it was 35mm cutting to HD and a dry shot cutting to an underwater one, the shots fit together seamlessly.

Amphibico housings are built specifically for a given camera. Because the HDC-F950 was new when The Cave was shot, the company adapted a housing for the F900 and developed a way to run fiber-optic cables into the camera to transmit power and audio and video signals. The housing gave the underwater operator full access to zoom and focus, while Nick Theodorakis, the HD engineer, controlled color and iris from above the surface.

Theodorakis and Lenzo also hacked into the internal comm board of the camera and modified it so it would integrate with an Ocean Technology Systems communications system. This allowed, for the first time, fluid communication among all parties working both above and below the surface, even when the underwater crew was deep within the caves. “When we were going in the full length of the fiber cable — 1,900 feet — I realized the image before me was of people who were half a mile away,” says Theodorakis. “It was mind-boggling to get perfect image and communication in one of the most dangerous places in the world.”

The image from the HDC-F950 was sent up through the fiber pipeline into a Sony HDCU-950 CCU camera-control unit. From there, the dual-link 4:4:4 signal was distributed into a SRW-5000 deck, which recorded the image onto tape in HDCam SR mode at full 1920x1080 resolution, compressed 4:1. At the beginning of the shoot, the filmmakers considered recording uncompressed footage onto a hard drive, but they found the difference between compressed and uncompressed footage almost impossible to discern with the naked eye — and they worried that recording onto a hard drive might be inviting disaster, given the conditions of the shoot. “I didn’t feel [the technology] had reached the point where we could bring it into the anti-tech environment of the Mexican jungle,” says Theodorakis.

Still, he adds that almost every 4:4:4 project he has worked on has taken place under challenging circumstances — rain, sleet, snow and hail — and he has had no problems. On The Cave, however, he faced two major logistical difficulties. First, electricity in Romania and Mexico was a little dodgy; he controlled the situation by keeping universal power conditioner backups going at all times. “Our power would just suddenly shoot down, but with those backups, we never lost a take,” Theodorakis reports.

The other problem was that the humidity level was at nearly 100 percent both on stage in Romania and in the Mexican jungle, and on the first day of prep in Romania, the team found that the deck would not record because of the moisture. Theodorakis and Lenzo discovered they could solve the problem by sealing the deck into its case overnight and pumping in nitrogen. “That would carry over for the entire day,” Theodorakis says. “Once we started doing that, we never had a problem.”

Emery had used HD on commercials before filming The Cave, and he says he’s very pleased with the way the format is evolving. “Over the last year or so, there’s been a change in direction from the companies supplying HD technology, and it has become much more friendly for feature production. Within the next few years, I expect the methodology to be refined even more.”

He notes that one of the challenges on The Cave was that the HD footage had to precisely match 35mm, and he found that the digital medium behaved differently in interesting ways. For example, when flashlights were pointed directly into the lens, “with film, the entire exposure lifted, but with HD, it didn’t — you’d get a bright spot and a flare.” He adds that in general, he felt fortunate that the movie’s imagery is so dark, because he noticed more differences between 35mm and HD in the highlights through mid-grays than on the darker end of the image.