Even if you are devoted to developing the perfect home movie theater, it is sometimes nice to go out and mix with the general public. For movie buffs, there are few more enjoyable nights out than watching a new release at an IMAX theater. With over 1,000 IMAX theaters in 69 countries there is probably one near to you.
A lot goes in to creating an IMAX experience as this article reveals:
Section 1: IMAX Film Stock and Movie Production
Shooting a movie on traditional 15/70 IMAX film stock presents big challenges in terms of cost and practicality. The 15 refers to the number of perforations that run through the IMAX movie camera at one time while the 70 refers to the width, in millimeters, of the film stock (or height in this case as the film runs horizontally through a projector). The frame size in an IMAX film reel measures approximately 70mm x 49mm which is almost ten times bigger than the 16mm x 22mm frames in movies filmed using standard 35mm film stock or the 19mm x 22mm Academy Format stock. This enables a far greater image resolution.
IMAX cameras are over 200 pounds in weight and that is before taking into account the additional weight of the film which has to be three times as long as 35mm film stock due to its larger frame size. The supports and rigging needed to move such a bulky and heavy piece of kit around a film set are considerable and the noise an IMAX camera makes is so loud that actors get irritated and all sound production has to be done post-shoot.
The incredible resolution IMAX can deliver poses its own problems with prosthetic and CG effects needing to be practically flawless to avoid shattering the illusion of reality.In 2011, IMAX brought out a much more manageable digital 3D camera and this was followed, four years later, by a 2D digital camera.
Section 2: IMAX Projectors
Before the introduction of its digital projectors in 2008, IMAX rolled out its four analog projectors.
15/70 film stock runs horizontally, a departure from the traditional method which feeds the film vertically through the projector. To prevent so-called ‘gate weave’ of this large film stock, the analog IMAX projectors use four stabilization pins at the corners of the frame and a vacuum system which sucks the film against a glass element set behind the lens. The lens is bigger than the frame and can be moved by a piston if it picks up dirt (although there is also a set of dust wipers for keeping the lens clean). A 15,000W water-cooled Xenon lamp provides the light source with projection assistants requiring body armor just in case the lamp should explode due to the intense conditions it operates under.
Unsurprisingly, the analog projectors are huge pieces of kit weighing as much as a car.
In 2008, IMAX revealed their much more compact digital projection systems. These combine two digital projectors which can be used to generate the separate images needed for 3D projections or two slightly out of phase identical projections in a standard movie. Together with a mechanism which uses feedback from screen-facing cameras to make sub-pixel adjustments, this dual image technology blends the pixels of the digital image to create an unlimited resolution. The colours in an digital IMAX projector are created by an ingenious mechanism involving chips, tiny mirrors and a glass prism. The downside of this is the creation of artefacts and wear and tear caused by constant temperature extremes. Contrast is also a big problem.
The latest addition to the IMAX projector family, first installed in Toronto, replaces the lamp and prism set up with a colored laser system. The laser system also uses dual projectors, each displaying four times the detail of its digital equivalent. There is also much better contrast allowing fine detail to be seen in dark areas of a frame even when others areas are bright.
Section 3: Sound and Other Extras
IMAX have also pushed the boundaries of sound experience with the latest systems adding six more audio channels (four speakers overhead and an extra two side speakers). Adding a headset, that increases the maximum audio channel capacity to 14.
The way IMAX deliver the 3D experience is also unique, combining polarized glasses and an LCD shutter system. With laser technology promising even greater color and detail to come, the potential for a jaw-dropping 3D experience is there.
3D is one area of movie experience that causes a lot of controversy and the same goes for HFR (High Frame Rate). HFR movies of 48 frames-per-second can be handled with IMAX cameras and projectors and have been experimented with by filmmakers such as Peter Jackson and James Cameron.
They produce a visually more realistic image than movies running at the traditional 24 frames per-second speed. HFR also makes the 3D experience less jarring to the eyes and there are fewer artefacts such as strobing during fast camera tracking. However, some viewers admit they don’t like the effect at all, complaining that the overall feel is of a documentary rather than a movie, so it may be wise not to make a 48fps movie your very first IMAX experience.
Section 4: The IMAX Canvas – Screens Over 20m High
The immersive IMAX experience is made possible by the vast screens in place at IMAX theaters and IMAX Domes. These screens are over 20m high with the biggest of them all (32m x 23m) currently housed in Melbourne Theatre, in a seven stories deep pit. Prior to its removal during renovation, there was an even bigger screen in Sydney at 35m!
IMAX Domes use a curved screen of up to 30m in diameter to fill the field of vision and heighten that feeling of being inside a movie.
Of course, even this technical wizardry can’t overcome some of the drawbacks of the movie theater – the $6 a bag popcorn, the long lines, the need to actually get dressed – but it is definitely an experience like no other and can give home movie theater builders a benchmark to work towards.