What is a giant-screen theater?
A giant-screen theater is a theater that boasts a screen up to eight stories tall; a special auditorium design, featuring "comfy," stadium-style seats; a state-of-the-art, mega-watt, six-channel sound system; and a giant-screen projection system, one of the most sophisticated motion-picture projection systems in the world. Working together, these elements immerse viewers in larger-than-life images and ultra-realistic sound, making them feel as if they are literally in the films—not just watching them.

Typically blending education with entertainment, the films shown in giant-screen theaters offer audience members the opportunity to visit fantastic locations around the globe and share in uncommon experiences. With Shackleton's Antarctic Adventure, viewers will not only be immersed in the barren, yet beautiful Antarctic, an environment where they wouldn't ordinarily be able to go; they also will be transported back in time to experience what has been called the greatest survival story of all time.

What makes this extraordinary realism possible?
First and foremost, the giant-screen film experience begins with super-sized 70mm film—the largest ever used in motion-picture history. Called 15-perforation/70mm film, it is 10 times the size of the 35mm film used in conventional cinemas, which means that it captures and holds much more information than a 35mm film frame does.

15-perforation/70mm film is also three times larger than standard 70mm film. In fact, in the late 1960s, the inventors of the IMAX motion-picture format, the one used by the majority of the world's giant-screen theaters, took a standard 5-perforation/70mm film frame; turned it on its side, so its perforations ran along the top and bottom of the frame, rather than its sides; increased its size by three; and then created a projection system capable of projecting this new film format (which is done horizontally—rather than the traditional vertical method).

What do these film-frame facts mean to giant-screen theatergoers?
Film-frame size has a direct correlation with picture clarity. Because giant-screen projection systems project the largest film frame in the world, they are able to project the world's largest images. As a result, viewers are immersed in multi-story visuals that are crystal-clear. These images fill viewers' peripheral vision, when projected onto screens up to eight stories tall in auditoriums featuring stadium-style seating. Because the super-sized images appear true-to-life, viewers feel as if they are transported into the films.

How is this super-sized film projected?
Not surprisingly, giant-screen film must be projected by a unique giant-screen projection system. The IMAX projection system, for example, is among the largest and most advanced projection systems ever built. The total weight of the projection system is 4,200 pounds, with each take-up reel measuring four feet in diameter and holding 70 minutes of film, weighing 200 pounds.

The light source for the IMAX projector is a 15,000-watt Xenon bulb that is stronger than the 12,000-watt bulbs originally designed as searchlights for U.S. Army helicopters or the lights used by NASA to illuminate the Space Shuttle launching pad. The bulb is water-cooled and lasts about three months.

The IMAX projection system has a massive lens and shutter, which transmits one-third more light than shutters in conventional projectors. The film moves through the projector in a special "rolling loop" projection system that uses compressed air instead of mechanical sprockets to advance the film in a gentle waving or rolling action.

During projection, each frame is positioned on fixed registration pins. The film is held firmly against the rear element of the projection lens by a vacuum. The result is picture and focus steadiness far above normal standards and previously unattained in giant-screen formats. The mechanism is so gentle that a film can be shown 2,000 times without significant wear.

What about giant-screen sound?
Image size and projection isn't everything in a giant-screen theater. The super-powerful, often-digital sound system provides half of the "giant-screen experience." Many giant-screen theaters boast 11,600 watts of power emanating from 44 speakers positioned in seven clusters around the auditorium. The sound moves in sync with the visuals, making the experience even more realistic.

With an IMAX sound system, for example, the high-fidelity, six-channel sound has four screen channels, two surround channels and a sub-bass system, providing depth to the sound. Visitors feel, as well as hear and see, the action. If a train is racing across the screen, the sound follows the path of the train. Adventure scenes seem real because of the depth and breadth of sound in motion.

In Shackleton's Antarctic Adventure, the soundtrack complements each and every image, for example, with the sounds of the crunching of the pack ice in the Weddell Sea or the hurricane winds and waves that Shackleton and his crew faced on their lifeboat journey to South Georgia Island.

How is a giant-screen film shot?
Giant-screen films are filmed with giant-screen cameras, which are considerably more complex than any other motion-picture camera systems. This sophistication comes with drawbacks, however. The cameras are heavy, weighing up to 80 pounds, and typically hold only three minutes of film.