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IMAX The TheGiant GiantMovie MovieSc S 8  Silicon Chip www.siliconchip.com.au Most readers have seen or heard about IMAX – the giant screen which can show movies in two and three dimensions (3D). This is the story of IMAX. By BARRIE SMITH P EOPLE ARE ENTRANCED with the big picture. In the early 1800s, Robert Fulton amazed audiences with his Cyclorama, a 16-metre high by 130-metre long painting that ran on rollers. The Lumiere brothers, not content with their pioneering 35mm film efforts, even managed to screen movies shot on 75mm film. The 3-strip 65mm Cinerama process emerged in 1963, quickly followed by CinemaScope, VistaVision, Circa-rama, Technirama, Todd-AO and so on. Then came IMAX, a process that side-stepped the perception that audiences just wanted a big, wide picture. Instead, the Canadian developers of the IMAX process headed for a screen picture that was just huge . . . very enveloping, very sharp and almost grainless, swamping the eye’s peripheral vision; the field of vision is 50° vertical and 130° horizontal. X The IMAX camera uses 65mm negative film (from which 70mm projection prints are made). An IMAX film frame measures 48.5mm high by 69.6mm wide – a total area of 3375.6mm2, over 10 times the frame area of conventional 35mm film. Each IMAX film frame has fifteen perforations; a single frame races past the camera’s aperture in 6 milliseconds; each second, 1.7m of film rips past; each minute exposes an ex­ pensive 102.6 metres of Mr Kodak’s famous product. A Cumbersome Beast The discipline required in shooting an IMAX production is extraordinary. A 2D camera can be a cumbersome beast, even though there are smaller units for difficult location work. In IMAX, it is advisable to avoid pans or quick movements of the camera. Sharpness and the utmost depth of Every way you look at it, IMAX is big. The diagram at left compares the IMAX filmstrip (also shown below) to ‘normal’ 70mm and 35mm. creen Screen www.siliconchip.com.au April 2003  9 Australian producer, Michael Caulfield (seated right) working on his film “Horses – The Story of Equus”. field is essential. Then there is the 3D camera, with its doubled film path and optics! Australian producer, Michael Caulfield has made two IMAX films: “Africa’s Elephant Kingdom” and “Horses – The Story of Equus”. In his experience “Wherever you turn in the IMAX format you’re going to have problems . . . the camera is very big; this means very, very big mechanical gearing and cogs to pull the film past the lens at a stable rate. “There are really only about 10 decent cameras in the world. They’re worth a lot of money and they’re also quite peculiar, so you have to send your camera assistants and focus pullers, if they’ve never worked with one before, to Toronto to learn it. “You have to book the camera a long way ahead”, Caulfield cautions. “You have to be able to schedule and re-schedule with a fair degree of certainty. And of course The Sydney venue at Darling Harbour is profitable, relying on 65% audience attendance of Sydney residents plus local and overseas tourists as well as school groups. In Sydney’s IMAX theatre biobox, chief projectionist Tim Gunn fires up the 2D/3D projector. 10  Silicon Chip www.siliconchip.com.au The schematic of Ron Jones’ “Rolling Loop” invention which is the core technology of IMAX projection. if you’re making natural history films that can be very difficult”. He has found the cameras are “surprisingly, very reliable. They have to be heavy-duty, otherwise yanking that amount of film through, they’d fail”. “However, if they do ‘go’, explode inside or the film snaps, they internally haemorrhage. It takes you ages to fix them”. Costs are another matter. “Every roll of film is 300 metres or three minutes long. Film and processing cost is about US$8000 for each roll. That’s just stock cost and processing. If you want to do print-downs to 35mm, which we do for everything we shoot, then that’s another cost altogether”. I asked him what is the shooting ratio (raw film shot vs final edited length) on a typical film. Caulfield: “A normal natural history film is around 30:1. We shoot around 11:1. You have to. You just can’t afford any more”. “And you have to make a lot of IMAX rotor paths: the right eye is uppermost and its aperture slightly advanced on the left. In these shots, film travels right to left. www.siliconchip.com.au Ron’s Loop The late PRW (Ron) Jones created a rolling-loop film transport for projectors in the ‘60s, the invention revealed in a paper given at the SMPTE in 1969. The young IMAX group snapped up the patent for its process, having realised that while you can whip 100 metres or so of 65/70mm film past a camera gate’s intermittent movement once, it won’t survive repeated journeys in a projector. In the projector, the primary film drive is by means of a 952.5mm diameter rotor with eight windows and driven at 180 RPM by a synchronised 3-phase motor. Pulsed air jets at each of the windows form a loop or wave in the film as it passes the input sprocket and then advances the film past the aperture; here a cam and four registration pins momentarily hold each frame in the plane of the aperture against a curved quartz glass rear lens element. Steadiness on screen is high – less than 0.04% in any direction; print life can run to at least 1500 showings. Norman McLaren Scottish-born, Canadian resident, Norman McLaren was determined to explore new techniques. The late 1940s, early 1950s saw him experiment with animated 3D films and hand-drawn films, scratching and painting not only the film image but scribbling and gouging over the soundtrack area to make his own audio effects. Still well ahead of his time. Wescam Arguably the world’s best gyro-stabilised camera platform, Wescam was first used in 1969. Today there are hundreds used worldwide by TV news crews and police video units. But the really heavy use is by a handful of 35mm film units in major world capitals. Its capabilities to produce rock-steady shooting at low frame rates (12fps for example) and with long lenses (such as a 250mm telephoto) has helped the creation of memorable images in the cinema. The Wescam mount uses three high speed gyros that control the roll, pitch, and yaw axes; a fourth gyro attends the vertical axis and helps further stabilise the camera platform when acceleration, deceleration and April G forces impinge on2003  11 the mount. successful IMAX theatre in the world, most times running in the top three or four. About 65% of its business comes from Sydney metropolitan residents, 15% from school groups and the remainder a mix of domestic and international tourists. Sydney IMAX has found that 3D titles are proving more and more popular. As Mark Bretherton, Sydney IMAX Marketing Manager, says: “A 3D film can actually be weaker in terms of content but it will draw more. The most successful films in 2001 were two 3D films, “Cyberworld” and “Haunted Castle”, plus a 2D film called “Shackleton’s Antarctic Adventure” (still running in early 2003) and probably one of the best crafted IMAX films I’ve seen”. Projection Top Gear Clever dual feed/takeup spools enable the next film to be nearly laced up, ready for showing. allowances as well because you don’t really ‘see’ the film until you’ve ‘locked off’ the edit. You can’t afford to print out everything you’ve shot onto 70mm. So what happens is that every so often you’ll print up a roll or two of shots you may be concerned about. “You cut the film on a digital editing machine from 35mm print-downs. That’s all fine and well but you don’t really know until the film is finished and locked off. The lab strikes a first answer print and then you look at it and you go ‘Oh my God!’ There may be a shot with a tourist van in it or the shot has a bit more shake than you thought, which renders it unacceptable. So you need to have an allowance in your budget to go back and reshoot”. Perched way above the audience in the Sydney IMAX theatre is the projection biobox, operated on most days by chief projectionist, Tim Gunn. He well remembers the days of short reel changeovers and, in one way, welcomes IMAX’s approach where the loaded film will run 40 minutes or more from the one roll. However, the call for “action stations” at reel’s end sees him race into top gear. A 2D print can weigh around 100kg so a forklift is used to trolley the film rolls around the biobox. The Sydney projector is a 2D/3D machine, fed by two film paths – or four for a 3D title. The films are threaded all the way to the projector input. At the end of a screening, the machine is stopped and the tail unlaced. Then the lacing up of the new print(s) commences. Normally the 2D and 3D films alternate; in this case Tim will take “a good 10 minutes” to make the change-over. This entails the lace-up and the change of projector optics and back condenser lens as well as a clean-up of the film path itself. The lenses are different for every theatre, depending on the projector-screen throw. Sydney has a Leitz Canada 38mm 2D lens and two 52mm lenses for 3D; the projected 3D screen image is Sydney IMAX Cinema The purpose-built Darling Harbour building is owned by MTM Entertainment Trust. The projection equipment is owned by IMAX Canada and leased to the Sydney company while the films are rented. There are IMAX cinemas in Sydney, Melbourne, Dreamworld at Coomera in Queensland and one in Townsville. The Sydney venue is the eighth most 12  Silicon Chip Yes, you need a forklift to move the 100kg film loads. www.siliconchip.com.au IMAX in space: Expedition 1 Commander Bill Shepherd (left, pale shirt) and Flight Engineer Sergei Krikalev (right) frame and focus a shot on the Video Display of the IMAX 3D cabin camera just before filming in the U.S. “Destiny” lab module of the Space Station. (Photo: NASA). smaller, because it “eats a lot more light”, thanks to cross-polarisers on the projector and those in the audience viewing headsets. Light loss is estimated to be at least 30%. Early on, the Sydney cinema used the original electronic 3D system which employed pulsed LCS (Liquid Crystal Shutters) as well as the cross polarisers. This method has given way to polarisation due to audience theft of the headset battery packs! Lamp power is from two 15kW xe- nons; the illumination is directed to the film aperture/lens point by means of a folded light path, using two aircooled mirrors. The projector itself is massive and aside from the dual light source and lens assemblies, has a double deck rotor to transport the films (see “Ron’s Loop”). The right eye film is uppermost. An interesting feature of the setup is that the left-eye film is projected a few degrees of rotation before the IMAX First shown at Expo ‘70 in Japan, the wide-screen process has been with us for decades and one of its earliest achievements was the 1984 Challenger and Discovery missions which were chronicled by an IMAX camera carried on three missions. The 14-astronaut crew were trained as movie cameramen for five months. The camera was the largest ever to travel in a space shuttle and needed special accommodation in the zero-G conditions. The whole scheme, comprising IMAX cameras, projectors, theatre design and sound system, was conceived in Toronto, Canada with virtually no input from Hollywood. A specialist Norwegian engineer built the first camera; the camera and projector lenses came from Germany and Japan; the first projector was built in Toronto – and the mechanical heart of it invented by Ron Jones, a Brisbane engineer. Generously, Hollywood recognised this innovative ‘heart’ – the rolling loop film transport – by awarding it an Oscar for technical achievement. OMNIMAX This is IMAX with ‘the roof rolled back’ and first seen in 1973 in a US planetarium. A Leitz f2.8/29mm fish eye lens is used to throw a razor sharp picture onto the inside of a spherical section, similar to a planetarium. The picture overfills your peripheral vision. The Townsville OMNIMAX screen forms a 160 to 165° segment of a hemisphere. The screen and audience are tilted at an angle of 25°, with the projection lens located a short distance beyond the hemisphere’s centre. The Edge The Edge, at Katoomba, NSW, is a purpose-built cinema, designed to run a 70mm format as well as 35mm movies. It was developed by ex-Disney veteran Ub Iwerks. The format uses eight perforation 70mm film running vertically. Frame area is 1775 sq mm – 5.5 times that of 35mm at 319 sq mm. And here’s a frame from the result, the first IMAX film in space and in 3D: Space Station 3D. www.siliconchip.com.au More IMAX? The IMAX process was described in much more detail in an article in “Electronics Australia”, February 1972. SILICON CHIP can supply reprints of this articel for $8.80 including GST and postage. April 2003  13 Twin rotors and twin film paths are the secret to the elec-tronic 3D on-screen image. The offset is about 12° or 0.01 seconds approximately. The original electronic 3D system employed pulsed liquid crystal shutters as well as cross polarisers. This method has given way to polarisation, not for technical reasons but due to audience theft of the headset battery packs! other film. This rotor offset (about 12° or 0.01 seconds approximately) allows the rotary shutter to expose the left lens and fire the left lens of the E3D viewer, while the right lens remains covered and the right E3D viewer LC lens is closed – then vice versa. The rotor offset ensures that the projected image is not partly obstructed by the rotor shutter. As you might expect, most functions are computer controlled. Below is the projector LCD control touch panel. Multi-track sound IMAX has had multi-track sound while suburban cinemas were still living in caves – so to speak! IMAX originally began with a 6-track 35mm magnetic dubber. The sound source is synchronised by projector drive shaft-encoded pulses. The IMAX sound system is quite distinct from Dolby. It was developed by Sonics in Alabama, now owned by IMAX. It is basically a 6-channel system with left, centre and right signals coming from the front; left and right signals from the rear, plus there is a channel issuing from the top of the screen for effects. Another channel, using a subwoofer with a stack of eight 15-inch drivers, derives its signal from all six channels. These days, the magnetic dubber is still used as back 14  Silicon Chip up but most times a setup of three digitally-synched CD players (Digital Disc Player or DDP) is employed, each carrying two channels per disc. Total running time is 80 minutes. There is also a 6GB hard drive system, becoming important as a sound source for longer, feature-length films. Some films use all three sources. SC www.siliconchip.com.au