IMAX movies are a treat. Big screens, wonderful surround sound, the awe of crystal clear 70 mm film. You’ve probably seen an IMAX screen at a science center or a local movie theater near you. What makes them different than other films? Why would directors and cinematographers choose IMAX format? Hopefully I can shead some light on the infamous IMAX experience.
IMAX is an acronym for Image maximum. IMAX film is known as 15/70 film format. That means that each frame is 15 perforations wide and 70 millimeters high, making IMAX film about 10 times bigger than the standard 35 millimeter film we see in normal movie theaters. IMAX screens are also much bigger than ordinary movie screens. The two types consist of a dome that wraps around the entire theater, and an IMAX theater with a large rectangular screen. The sheer size of the film and the screen prevents it from being able to be projected with a 35 mm and normal 70 mm projector, so IMAX has created their own. One with a vacuum to suck in film, a slower shutter, and a water-cooled xenon bulb to make the image brighter. The end product weighs about two tons and is the size of a small car.
The result is a very clear, bright image that fills your field of vision. The motion and light is so clear and vivid that some can get ill from watching. If you are worried about that, try and sit as far back as you can. IMAX theaters also have an advanced sound system with 6 different channels, sometimes more.
Now, you’re thinking, I’ve seen an ‘IMAX’ movie in what seemed to look like a normal theater. No you did not get ripped off! IMAX DMR stands for digital remastering. They take 35mm film and put it in a higher resolution to extract important image elements to make the footage even clearer than the original digital version. This can upgrade the resolution to 2K or even 4K. They then have two 2K (or 4k with laser projection) projectors play at the same time in order to achieve projecting on a smaller screen. In order to get IMAX 3D, polarizing filters are added to the film and the audience wears glasses with other polarizing filters, creating a 3D image.
How do these images first get created? Well, there is a special IMAX camera that one must use to get the highest resolution possible. The camera is giant compared to other industry standard cameras. An IMAX camera is about 240 pounds and needs special rigging and supports in order for it to move around. This is much more than the industry standard cameras, like the Arri Alexa which weighs 40 pounds. Not only is it huge, it makes a loud noise like a buzzsaw that affects everyone on set. All sound must be recorded after the fact, which can be a lot of work. Everything about IMAX is giant, so it’s not surprising that renting this camera costs about $100,000 a day. Even with these challenges, many directors still find it worthwhile to use IMAX cameras to achieve the highest resolution possible to tell their stories.