Ever since motion pictures were first created, the industry has continually invented ways to further impress audiences. One of these improvements was the IMAX system which allowed screens to be much bigger and visually impactful than standard film. But achieving this simple upgrade took a great deal of engineering.
Every step, from shooting the film to projecting it, requires special equipment and an incredible amount of work.
For example, to project an IMAX feature film, up to 60 reels have to be spliced together to create one continuous film that could be over 10 miles long. Even the projector itself is massive and requires a special vacuum system, compressed air systems, and a water-cooled quartz bulb.
IMAX has largely converted to digital projection which has eliminated many of these technical challenges. However, there is a trade-off since the maximum resolution of an IMAX digital picture is estimated to only be 1/4 of IMAX film. IMAX estimates this film to be equivalent to 12K resolution.
About the Bulb:
The IMAX projector utilizes two 15,000-watt liquid-cooled, short-arc xenon lamps. The lamps weigh 10 pounds each, and are nearly two feet in length. Costing more than $6,000 each, the lamps have a life expectancy of only about 1,200 hours of operation and are replaced 4 times per year. Because of the extreme high-pressure xenon gas inside the quartz glass envelope of the lamp, projectionists must wear ballistic safety gear when changing out a lamp. If dropped, the xenon lamp would explode with the destructive force of a hand grenade.
The average luminance of one of these xenon lamps is approximately 1.6 billion candles per square yard--about equal to that of the Sun as viewed from the Earth's surface! The lamp has a light output of approximately 600,000 lumens. NASA uses this same type of lamp at the Kennedy Space Center to illuminate the Space Shuttle at night on the launching pad.
During normal operation, the clear quartz glass envelope of the lamp has a surface temperature of about 1,300 degrees. To prevent the lamp from overheating, it has coolant "jackets" that allow cool distilled water to be pumped around the electrodes at the flow rate of 8 gallons per minute and a pressure rate of 100 psi. In addition, an exhaust fan removes 1,200 cubic feet of air per minute from the lamphouse. The xenon lamps operate at 37.5 volts DC, and 400 amperes of current.
A Few More Interesting IMAX Facts:
- IMAX picture and sound are recorded onto 2 different sets of film.
- An IMAX film can cost up to $36,000 to print vs $1,000 for a standard 35mm film.
- The film is sensitive and requires that the projection room remain at 68–75°F & ~50% humidity.
Want to dig deeper? You might enjoy the IMAX Technical Manual for Filmmakers (pdf)
