IMAX works by running a 70 mm film through the projector not vertically, but horizontally. An IMAX frame is ten times as large as a frame of traditional 35 mm, which requires the film to run at a speed of 103 metres per minute. A 40-minute IMAX film is thus four kilometres long and weighs 60 kg.

The usual Maltese cross mechanism cannot be used to transport an IMAX film; it would rip it apart. Thus, an 180 rpm rotor is used to transport the film, without traction, across the projection window, against which it is sucked by an aspirator. Xenon lamps of several kilowatts project an image that can be larger than 600 square metres.

IMAX 3D is, well, IMAX in 3D. It works with a flat screen and polarisation glasses. There is a successor to the IMAX technology, Omnimax, where an IMAX projector with a fisheye lens projects an image on the inside of a hemispherical dome, which can be 900 square metres large. The nec plus ultra of modern cinematographic technology is, however, Omnimax 3D, which combines the hemispherical screen with 3D, done by shutter glasses. It immerses the spectator in a three-dimensional field of vision that stretches 180 degrees in every direction.

This writeup compiled from: Henri Cormier, La technique au Futuroscope, Hachette Livre (Hachette Tourisme) 1996.

Comment - For all you non-geek types, the biggest design impact of 3DImax is that it makes "normal" movies almost impossible. Imax screens are something like 5 stories high. Close-ups of people talking just don't work when the participants are that big. This is one reason most Imax films don't generally do this (plus the camera sounds and is as loud as steam train engine)

But do this in 3D and that 5-story-tall head is just the right size. The large screen fills your field of vision and provides the kind of depth that you have to experience.
Of course, 3D also has big effect on how you layout and design the scenes.... but I'm just a technology geek :-)

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