It might be Easter, but last night was Christmas. No, really: I was invited to a private « behind-the-scenes » visit of the IMAX theatre at Canada Place. Now, I’ve always been a big fan of the IMAX technology, just because it’s bold and it’s good and it’s large and it’s daring. But thanks to John, the senior projectionist, I spent an hour and a half in movie wonderland, on the other side of the curtain – so to speak – and the IMAX magic finally evolved in my mind from a hazy mystery to pure technological madness.

There’s nothing reasonable about IMAX. At 70 mm and 15 perforations, the film frame is the largest ever designed, 10 times bigger than normal 35mm film. The camera required to initially record images on such large stock is gigantic. Conventional cinematographic techniques must be adjusted for such scale; the 5 to 8 storeys high IMAX screen will show a whale at its actual size. Then in comes the 3D edge where twin lenses record a stereoscopic image on two different film rolls that will be projected simultaneously and polarized, to be viewed through similarly polarized glasses. And then there’s the sound: 6 channels of pure thunder.

John knows his stuff, he’s been doing this for over 8 years. When I arrived, a movie was finishing. He initiated the switch over sequence to the next movie while explaining what he was doing. « I don’t want to interfere with your timing », I told him worried that my presence would be distracting. « No problem » he answered with a smile, « I know exactly how long this takes. 12 minutes. But I can do it in 6. » I sensed a very legitimate touch of pride there, as he was literally gliding above the ground of his projection room, winding here, switching there, lining this up, cleaning that up, adjusting some things, controlling others, and commenting all along.

The IMAX projector at Canada Place was installed for Expo ’86 and became the first permanent 3D setup. It’s not the most current design and yet it is totally space-age. Of course when I talk about « the projector », I should say « the projectors », since there are actually two of them, each handling its own roll of film, a left and a right, that end up forming the 3D movie. They are mounted on hydraulic platforms to allow moving them apart for easy access between movies.

Powered by arc-welders installed on a lower floor, the projectors are air-cooled by a compressor. The lamp themselves, 15,000 watts of pure xenon power – it is said that if one could be installed on the moon, it would be visible to the naked eye down on Earth – are water cooled. They generate so much heat that they could ignite a piece of wood placed near the film plane. John explained that the lamps, each worth some six thousand dollars, are so dangerous that he has to wear special impact-protection clothing when changing them.

He proceeded to rewind the right film, the left projector having been upgraded to a newer system loading the film from the inside of the roll and transferring it to a new plate, where it is ready to play again. Then he started loading Deep Sea 3D, my favourite IMAX movie of all times.

The heart of an IMAX setup is the innovative film transport system called Rolling Loop which breaks all the rules of traditional film projection. While a conventional projector simply drives the film in front of the lens with the intermittent help of a wheel grabbing the perforations as they become available, making the whole process too shaky and unsteady for IMAX quality, the Rolling Loop does much more. It uses a continuously revolving mechanism which advances the film horizontally (IMAX movies are thus projected horizontally rather than vertically) in a smooth, wave-like motion. During projection, slack sections of film exactly one frame long are formed in special spaces; then each frame is positioned on fixed registration pins, and the film is held firmly against the rear element of the lens by a vacuum. As a result, the picture and focus steadiness are far above normal standards.

IMAX film rolls do not include an embedded soundtrack as do conventional films. Instead, the 6 channel soundtrack comes on a DVD. It is loaded onto a computer hard drive and read by the Digital Theatre Audio Control (DTAC) system which distributes it directly to the amplifiers without the need for decoding as with Dolby. The soundtrack is initially synchronized to the movie with the help of special cue frames and the DTAC then locks the movie and soundtrack together. With 14,000 watts of power, sound quality is unsurpassed and perfectly even, regardless of where one sits in relation to the screen.

I stared in awe, speechless. Down below, in the theatre, the audience was smiling at the dance of turtles getting their shells cleaned by schools of colourful fish, on a perfectly chosen soundtrack. They probably were tempted to extend their arm through the air and touch the turtles which appeared so close and so real. But I could have done better; I could have reached out and actually touched the film, as it was rushing past me towards the projector at a speed of over 300 ft/min. I was in the projection room of an IMAX 3D movie theatre. I was behind-the-scenes of a movie system ahead of its time. I was in a sorcerer’s lair watching a sacred ritual. I believed in magic.

2007-04-08 22:49 • Posted in Bits and pieces: & Cool: