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At the September 24, 2005 meeting...
An IMAX Technical Journey
From Humble Beginnings to Big Screen Powerhouse


After nearly two years of phone calls and e-mails with the IMAX Corporation, we were finally able to offer this special Saturday morning technical presentation and film screening at the new Jordan's Furniture Comcast IMAX 3-D Theater in Reading, MA.

IMAX Corporation's Senior Vice President of Technology, Mr. Brian Bonnick, P.Eng., came down from corporate headquarters in Canada and gave an excellent presentation.

The story of how IMAX came to be was inspiring in itself. It started with a group of filmmakers who made multiscreen presentations for Expo '67 in Montreal. At that time, sensory-surrounding experiences were shot with multiple cameras and shown with synchronized projectors. The camera gear was very cumbersome - several film cameras rigidly bolted into a rack to cover a full arc of view. And the projection equipment was equally clumsy - as well as needing to be mechanically synchronized. And the prints needed to match...

After the exhibition was over, they gave some thought to how one might be able to make these productions on a single large roll of film - 72mm film fed sideways so the frame is about three times the size of a regular 72mm print image. It turns out that a camera is fairly easy to build, but projection was a big problem: The larger film size has more mass, which makes it harder too accelerate and stop at the film gate. They weren't able to get the jitter down to acceptable levels and the greater force used to move the film was tearing the sprocket holes. So it seemed for a while that IMAX would remain only a dream...

Then they saw an article by an Australian tinkerer who had invented a sprocketless projection system - he spooled the film in a big loop and moved the individual frames with a small propagating wave. It sounded kinda loopy to me - looked funny in the drawings too - but the videos that Mr. Bonnick showed demonstrated that this simple system works quite well.

IMAX was ready to go!

The next component of the IMAX experience is the theater construction, which they supervise closely. The screens are placed very close to the audience, curved for consistent focus, and painted with a special high-reflectance paint. The projectors are designed for consistent quality and maintainability (the lamps come is special pre-focused housings)  and a very high-quality audio system is installed that utilizes custom-built speakers.

And then there's the movies: IMAX rents cameras out to producers who want to make IMAX films, but they also take existing films and repurpose them for IMAX projection. They don't just print them on the bigger stock - they scan in the negative and do median-type filtering to remove grain. They also have a process that can make a regular movie 3D! They use a mixture of automated and manual techniques to do this and the clips they showed us from some of the recent Spiderman and Harry Potter movies were pretty spectacular. Finally, they can also generate CG 3D animated movies by rendering from two viewpoints and Mr. Bonnick showed us some excerpts from The Polar Express, an animated 3D film that was a big hit for them.

Finally, we got to see the newest IMAX release - a movie about the Apollo moon missions. The dramatizations of what might happen if an astronaut had an accident were really convincing.

To top it all off, Mr. Bonnick handed out samples of IMAX film. It was an excellent meeting and could only have been improved if they had allowed us to keep the polarized 3D glasses.

-Bob Lamm.

Posted: 12 October 2005
Bob Lamm, SMPTE/New England Newsletter/Web Page Editor
blamm@cync.com