There’s a reason why most modern cinematic releases are filmed digitally.
True, traditional IMAX filmmaking is not for novices. The entire process is time consuming, not to mention expensive. Most filmmakers aren’t making their next movie using 70mm IMAX film, and if there’s one point to blame, it’s probably to do with the camera.
An IMAX 15/70 film camera is very bulky and expensive to operate. Even if we assume that money isn’t a problem, they’re loud. Very loud. You can expect to hear a non-stop mechanical whine when you start rolling with an IMAX film camera. The enormous strip of film that races through it has to be held completely flat while each frame is exposed, with the vacuum system that performs the role just adding to the noise. Combined, you’ve got a camera that might capture outstanding-quality film, but isn’t particularly easy to work with.
An IMAX camera moves a huge amount of film
We’ll need to go back to basics to explain why an IMAX camera is as loud as it is. Film cameras record a series of still images. Each frame must be held motionless behind the lens while it’s exposed, with the camera advancing the film and repeating the process. That entire cycle usually happens 24 times every second with a standard cinematic film camera.
An IMAX camera has much more film to move, quite literally. The format is known as 15/70 because each frame on a 70mm projection print spans 15 perforations, or sprocket holes, which are the small holes that run along the edges of the film that help the camera position each frame. During filming, the camera runs a 65mm negative horizontally, again using 15 sprocket holes for each frame rather than the five used by a conventional 65mm camera. The resulting image ends up being roughly three times larger.
At 24 frames a second, that’s 360 sprocket holes of film a second. That’s 5.6 feet per second, or 336 feet a minute. Each 1,000-foot film magazine provides around three minutes of recording time.
It’s important to make clear how expansive this operation is. That’s a lot of film, both in size and weight. Moving it requires a powerful motor. The movement, not to mention the camera’s magazine and shutter operation, are adding more noise into the mix. The film has to repeatedly move and settle into place. The sheer size of the film and camera involved, and the speed it needs to work through, helps create a mechanical rattle that you’ll probably hear in behind-the-scenes footage, like this clip showing IMAX 15/70 film cameras on the set of Nope.
The vacuum system creates a constant whine
While film that big and heavy is a noise problem for IMAX cameras, it’s only part of the problem. With each frame needing to sit completely flat behind the lens, the film can easily retain some curl after it’s been wound inside a magazine. A small bend that breaks the plane of focus can ruin the entire film.
To fix it, IMAX cameras use a vacuum plate behind the lens. It creates 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’s not there to force the film through the camera, but only to help position each frame accurately.
To create the vacuum, you need suction that’s running as the film moves through the camera. The pump and movement of the air creates one of the biggest quality-of-life issues with traditional IMAX cameras. You’ll hear a high-pitched mechanical hum that can badly affect the recording process in the wrong environment. If you lose the suction, you risk film bends that affect the quality of the film.
Filmmakers have several ways to hide the noise
The noise is one of the reasons why IMAX movies aren’t the dominant format in movie theaters. Most modern cinematic releases are filmed digitally, and those that aren’t are probably using cameras that are less bulky and expensive.
For instance, “Filmed for IMAX” movies like Mission Impossible: The Final Reckoning don’t use film at all, but they’re still shown in IMAX movie theatres. They use IMAX-certified digital cameras and feature scenes that use the expanded 1.90:1 aspect ratio, but because those cameras are entirely digital, the noise issue is avoided.
Even without a digital IMAX camera, there are still a few ways to offset the noise pollution, although it doesn’t remove it completely. While IMAX cameras don’t lend themselves to small, intimate sets or quiet moments of dialog, they’re perfect for big action scenes with lots of noise. We’ve seen this used in No Time to Die, with its IMAX cameras used mainly for action and stunt sequences with minimal dialog. Any dialog spoiled by the IMAX camera can be rerecorded later using automated dialog replacement, or ADR, in post production.
There are even some physical ways to offset the issue. A “barney,” a kind of soft-padded cover, can help reduce some of the mechanical sounds in IMAX setups. A “blimp,” meanwhile, helps to create a rigid soundproof enclosure to isolate some of the noise. The problem with this is the weight. An older IMAX camera in a blimp can weigh as much as 275 pounds: this isn’t the ideal camera for a single operator to move around a movie set.
Some effort is being made to improve the technology, though. IMAX has already developed a smaller, quieter camera called the Keighley, used to film Christopher Nolan’s The Odyssey. It uses an all-new blimp design that allows the production to record synchronized dialog, helping to capture usable sound while shooting to offset the problem. It’s reported that the entire system weighed over 300 pounds.
Whether or not the new Keighley camera is enough to encourage more IMAX filmmaking remains to be seen. IMAX movies are premium experiences, but they’re difficult to film, and few filmmakers have so far shown a desire to make them. Loud IMAX cameras are just one of the reasons, and making the camera quieter doesn’t make things any cheaper or easier to handle.
