There’s a reason why most modern cinema releases are filmed digitally.
It’s true that traditional IMAX theater is not for novices. The whole process is time-consuming, not to mention expensive. Most filmmakers don’t make their next film using IMAX 70mm film, and if there’s any point of blame, it’s probably because of the camera.
An IMAX 15/70 film camera is very bulky and expensive to use. Even if we assume money is no object, they are loud. Very strong. You can expect to hear non-stop mechanical whine when you start rolling with an IMAX film camera. The huge strip of film running through it must be held completely flat while each frame is exposed, with the vacuum system that plays this role only adding to the noise. Combined, you have a camera that’s capable of capturing exceptional quality movies, but isn’t particularly easy to use.
An IMAX camera moves a huge amount of film
We’ll have to go back to basics to explain why an IMAX camera is so noisy. Film cameras record a series of still images. Each image must remain still behind the lens while it is exposed, with the camera advancing the film and repeating the process. This entire cycle typically occurs 24 times per second with a standard motion picture camera.
An IMAX camera literally has a lot more film to move around. The format is known as 15/70 because each frame of a 70mm projection print has 15 perforations, or sprocket holes, which are the small holes that run along the edges of the film and help the camera position each frame. While filming, the camera presents a 65mm negative horizontally, again using 15 sprocket holes for each frame instead of the five used by a conventional 65mm camera. The resulting image ends up being about three times larger.
At 24 frames per second, that’s 360 holes of film per second. That’s 5.6 feet per second, or 336 feet per minute. Each 1,000-foot film store provides approximately three minutes of recording time.
It is important to specify the scale of this operation. That’s a lot of film, both in size and weight. Moving it requires a powerful motor. Movement, not to mention the camera charger and shutter operation, adds noise to the mix. The film has to move and set up repeatedly. The sheer size of the film and camera involved, as well as the speed at which they must operate, helps create a mechanical rattle you’ll likely hear in behind-the-scenes footage, like this clip showing IMAX 15/70 cameras on the set of No.
Vacuum system creates constant moaning
Although such a large and heavy film poses a noise problem for IMAX cameras, it is only part of the problem. Since each image must lie completely flat behind the lens, film can easily retain some curvature after being wound into a magazine. A small turn that breaks the plane of focus can ruin the entire film.
To fix it, IMAX cameras use a vacuum plate behind the lens. This creates a suction that pulls the film flat against the plate during the exposure process. The camera creates a stable surface on which to record the image. It is not there to force the film through the camera, but only to help position each frame precisely.
To create the vacuum you need suction that works as the film moves through the camera. The pump and movement of air creates one of the biggest quality of life issues with traditional IMAX cameras. You will hear a high-pitched mechanical buzzing sound which can seriously affect the recording process in a bad environment. If you lose suction you risk bending the film which will affect the quality of the film.
Filmmakers have several ways to mask noise
Noise is one of the reasons why IMAX films are not the dominant format in movie theaters. Most modern cinema releases are filmed digitally, and those that aren’t probably use less bulky and less expensive cameras.
For example, “Filmed for IMAX” films like Mission Impossible: The Final Judgment don’t use films at all, but they are still shown in IMAX theaters. They use IMAX-certified digital cameras and present scenes using the wide 1.90:1 aspect ratio, but because these cameras are completely digital, the noise problem is avoided.
Even without an IMAX digital camera, there are still several ways to compensate for noise pollution, even if it doesn’t completely eliminate it. Although IMAX cameras don’t lend themselves to small, intimate settings or quiet dialogue moments, they are perfect for big action scenes with lots of noise. We have seen this used in No time to diewith its IMAX cameras used primarily for action and stunt sequences with minimal dialogue. Any dialogue spoiled by the IMAX camera can be re-recorded later using automated dialogue replacement, or ADR, in post-production.
There are even physical ways to solve the problem. A “barney,” a type of padded blanket, can help reduce some mechanical noise in IMAX setups. A “blimp,” meanwhile, helps create a rigid, soundproof enclosure to isolate some of the noise. The problem is the weight. An old IMAX camera in a blimp can weigh up to 275 pounds: it’s not the ideal camera for a single operator to move around on a film set.
However, some efforts are being made to improve the technology. IMAX has already developed a smaller, quieter camera called Keighley, used to film Christopher Nolan’s film. The Odyssey. It uses an all-new airship design that allows production to record synchronized dialogue, helping to capture usable audio during filming to compensate for the problem. The entire system was reported to weigh over 300 pounds.
Whether or not the new Keighley camera will be enough to encourage IMAX filmmaking remains to be seen. IMAX films are high-end experiences, but they are difficult to film, and few filmmakers have so far expressed a desire to make them. Noisy IMAX cameras are just one reason, and making the camera quieter doesn’t make things cheaper or easier to manage.
