Omnimax refers to an exceptional IMAX movie theater housed in the Museum of Science and Industry in Chicago, Illinois (among other places; briglass informs me that there is now one in St. Louis, MO). There are also other similar Omnimax installations at other industry and science museums throughout the world (I was informed of this by CrAzE and further research). The theater is essentially a massively oversized IMAX theatre housed inside of a small dome, meaning the effect is quite breathtaking.
The first thing you notice when you visit the theater is the sheer immense size of the thing. The dome measures 72 feet in diameter and is roughly five stories tall at its peak. The theatre contains 342 seats, the size of a large movie theatre, but the dome effect makes it feel much larger than that. According to the people at the museum, roughly 11 million people have seen a show in the theatre over the last few years since it opened in 1998. The screen itself covers most of one wall of the dome, making a very immense area for film projection.
The screen itself is made of perforated aluminum. The reason for this is severalfold. First, aluminum is relatively inexpensive, and a lot of it is needed here. Second, aluminum, when prepared correctly, serves as a very nice reflective surface. It isn't as nice as a top-quality theater screen, but it definitely does well. A third reason is that heated aluminum (at least to the low heats that the beamed lighting puts on it) doesn't expand very much at all. The perforations take care of all of the expansion that will happen. This is very important in terms of structure and stability of the mammoth screen.
The films shown here aren't your typical theatrical films. IMAX films are usually short documentaries, designed mostly to educate and show off the fact that IMAX films look great and produce a wonderful 3-D "being there" effect. In a theater of this size, the effect is quite impressive. The usual films shown at Omnimax are "The Human Body," which is a visual tour through anatomy, and "The Greatest Places," a tour of some of the better sights and sounds one might see in the world. Don't expect to see Jurassic Park or something because they were not shot in the IMAX format.
Along with the high-quality video, the IMAX format and this theater's exceptional equipment make for some nice audio effects. There are six channels of audio going on, amplified by forty amplifiers (producing over 20,000 watts of power). There are a ton of speakers as well; behind the screen, one finds twelve clusters of seventy two speakers that blast out the noise (the placement is possible due to the strength of the aluminum screen and the "give" that it has due to the perforation). You can often feel the force of it in there, and it is quite loud.
The IMAX film reels are enormous because they encode so much more information than a normal film. IMAX is shot in a 70 x 100 mm frame size, making for some very detailed and elaborate shots with great sharpness and clarity. The result, though, are film reels that weigh over 200 pounds, making loading and unloading the film quite a task.
The projector, like everything else, is massive as well. The bulb burns extremely bright with xenon gas inside the tube. It requires 15,000 watts (compare that to your household lights) and burns at a temperature that often approaches 6000 Kelvin. That's hot enough to melt pretty much any metal you can conceive of, so a lot of shielding and precautions are needed to keep the bulb safe. The bulb lasts for about a thousand hours and is quite a trick to replace, involving a ton of safety procedures and protective suits.
The end result is a truly amazing film-viewing experience. I have partaken in both films showing there currently, and they were both nearly mind blowing. The huge screen almost absorbs you into the film, and the sound is absolutely fantastic. If a theatrical film were ever shown like this, it would do unbelievable business.
Ticket prices for a show at Omnimax are between $6 and $15. You have to call ahead to get in unless you are extremely lucky; it is a very popular attraction at the museum and for good reason. Also, make your plans so that you see the film first during your visit to the museum; if you plan it just before you leave and the bulb burns out, you are simply out of luck. It is definitely worth seeing though, one of a ton of reasons to visit the thoroughly wonderful Museum of Science and Industry in Chicago.