Think big movie—big size movie, literally—and you have to think IMAX. An IMAX cinematic experience gives you images that are up to eight stories high, with six channels of digital surround sound thrown in. Think a complete-immersion-in-the-movie experience—a virtual immersion—and you have to think of IMAX. IMAX gives a complete 3D experience, wherein you can go inside the human body or scale the heights of the Himalayas.
So, what goes into the making of IMAX movies? But before that, what is IMAX? Just like Xerox has become synonymous with photocopying, IMAX, an entertainment technology company, has become synonymous with large size 2D and 3D movies. The word IMAX is derived from Maximum Image.
There are over 200 IMAX theatres spread across 30 countries. There are two in India, in Ahmedabad and Mumbai. IMAX theatres are used not only for general viewing, but also at zoos, planetariums and the like.
Film: bigger is better
The max effect comes from the size of the film used—IMAX works on 70 mm film, which is double the size of regular cinema-quality films that are made on 35 mm film. This by itself is not enough. Hollywood is familiar with using 70 mm film negatives and prints.
The secret behind the largeness of an IMAX movie is that the 70 mm film runs horizontally through both the camera and the projector (the width of the film is used as the height of the frame). The second secret is that there are 15 perforations per frame on an IMAX film, unlike in other 70 mm formats (a 35 mm film has four perforations per frame). This makes the surface area of a 15/70 film frame 10 times larger than that of the regular 35 mm film frame.
The IMAX theatre in Copenhagen, Denmark
Camera: extra large
Predictably, IMAX cameras are specially designed to shoot 15 perforation, 70 mm film. Apart from this, they have to be steady and versatile enough of being used in some out of the world places where IMAX films are shot, places like outer space, Mt Everest, and the ocean floor. These cameras weigh between 19 to 45 kgs.
Given the large format, an IMAX camera can hold only three mins of film at a time, after which it has to be reloaded. And the reloading time is 30 minutes!
Projector: stellar power
Lamps with a power of 15,000 watt each, one for each eye, when showing a 3D film, is what an IMAX projector houses. These lamps have a combined power output of 1 million lumens. This is about the same as that of the Sun when viewed from Earth. And the projector weighs about 1,365 kg.
It is also the projector technology, called rolling loop technology, that gives an IMAX movie its clarity and sharpness. This enables the film to move in a wave like motion at 24 frames per second, at a rate of 334 feet per minute. This speed is three times the speed of a 35 mm film. The result of all these: amazing size and clarity.
Sound: hear a pin drop
Its’ not just a stunning visual experience, but sound, too, that contributes to an immersive experience. IMAX theatres use 12,000 watt uncompressed, six-channel digital surround sound. The IMAX theatre in Ahmedabad has 44 speakers grouped into six clusters, which reside behind the screen and at the rear of the theatre.
Also, IMAX screens have thousands of perforations that allow the dramatic sound from the speakers to flow freely through the theatre such that you hear crystal clear sound no matter where you are sitting.
Screen: size matters
IMAX screens are of two types: flat and dome shaped. The flat ones are up to eight stories high—about 70 feet high and 80 feet wide. The dome-shaped ones are designed so as to take into account peripheral vision, both laterally and vertically. This is done by an encompassing 180 degrees dome, which is also tilted at 30 degrees. The projector in a dome theatre is not in a separate, far away projection room, but in the middle of the theatre. It rests on an elevator and can rise from 10 feet to 23 feet. The screens are made up of a special perforated vinyl to allow sound to travel through, and are painted silver to maximize the amount of light reflected back to the audience.
Your left and right eyes see an object from two slightly different angles, and your brain brings these two views together to form a single 3D image. How IMAX handles 3D is that its cameras have two identical lenses placed such that they match the distance between the two eyes (about 2.5 inches). This lets each lens see both the left and right views exactly as you would see them. The images register on two separate rolls of film on both the camera and the projector.
To see the 3D images, you have to wear either polarized glasses or a headset with electronic liquid-crystal shutter glasses. Not all IMAX theatres are 3D. About 100 across the world are.
You can either shoot a movie directly in IMAX, or digitally remaster an existing 35 mm movie into IMAX. This remastering is done using proprietary software developed by IMAX. After remastering, the movie has to be sharpened to fit the larger screen size of IMAX. This is also done on software. Once this is complete, the movie is transferred to IMAX film.