Dunkirk in IMAX 70mm Film and Dolby Cinema Digital


I’m definitely not a fan of war movies. I’ve never seen Saving Private Ryan, Platoon, Thin Red Line, Full Metal Jacket, Hacksaw Ridge, or just about any other war movie. By all accounts, some of them are cinematic masterpieces, but I simply have no stomach for watching such violence. So it was with great reluctance that I decided to see Dunkirk—not once, but twice in the same day! As a movie-technology geek, I wanted to compare the presentations in IMAX 70mm film—director Christopher Nolan’s first-choice format—and Dolby Cinema with Dolby Vision high dynamic range.

Dunkirk is “historical fiction”—that is, it’s based on historical events, but with fictional characters. At the beginning of World War II, some 400,000 British and French soldiers are trapped on the beach at Dunkirk, France, surrounded on all sides by the German army. As they try to escape on British navy ships, the Germans lob artillery from the land and drop bombs from planes, sinking many of the ships—even hospital ships. The Royal Air Force sends Spitfire fighters to stop the German planes, but they have too little fuel to fight for long after crossing the English Channel.

So the British government requisitions any and all private boats to sail for Dunkirk to help evacuate the soldiers. Among them is the Moonstone, which is owned by Mr. Dawson (Mark Rylance), who takes his son Peter (Tom Glynn-Carney) and Peter’s friend George (Barry Keoghan) along to assist. Meanwhile, back at the beach, Commander Bolton (Kenneth Branagh)—who seems to have been inspired by real-life Captain William Tennant—is in charge of the evacuation. Other notable characters include British soldier Tommy (Fionn Whitehead) and Spitfire pilot Farrier (Tom Hardy).

Nolan clearly wanted the movie to be as realistic as possible. In this interview on NPR, he talks about crossing the English Channel at the same time of year as the evacuation—May 27 to June 4, 1940—and weaving actual veterans’ accounts into the story. Also, he shot the beach footage in Dunkirk with real boats and planes rather than special effects. The result is surprisingly accurate, historically speaking; check out this article on Slate.com that explores what’s fact and what’s fiction in Dunkirk.

Perhaps most important, Nolan prioritized suspense over character development. As he says in that NPR interview, “The tone of the film is really about immersion, it’s really about first-person experience. There’s very little dialog in the film. The idea is you jump right in and you’re almost a participant in what’s going on.” The result is 106 minutes of non-stop, intense anxiety heightened by Hans Zimmer’s score, which consists mainly of long, dissonant drones over an insistent rhythmic pulse, almost like a clock ticking away the seconds. The only recognizable musical element is the triumphant Nimrod theme from Edward Elgar’s Enigma Variations at the end of the movie.

I found the structure a bit abrupt and haphazard. Scenes shift from the beach to the Moonstone to the Spitfires to the doomed ships with little apparent rhyme or reason. (One exception is the parallel scenes of soldiers in a sinking ship and a pilot in his sinking Spitfire.) Perhaps this was intended to increase the sense of anxiety, but it just seemed odd to me.

Nolan shot Dunkirk on 65mm film using IMAX and Panavision cameras. Undoubtedly, his first choice for presentation is IMAX 70mm film, so that’s where I started—at the AMC Universal CityWalk 19 IMAX theater. That screen measures 80×60 feet, and much of the movie fills it almost completely with an aspect ratio of 1.43:1. Most of the scenes on the “little ships” switch to a wider aspect ratio with letterbox bars above and below.

As expected, the black level was very high, especially compared with Dolby Vision, and the shadow detail in the few dark scenes was quite poor. In addition, I was shocked to see large sections at the top and bottom of the screen that were significantly darker than the rest of the image on bright scenes. Was this intentional, or was it a problem with the projection system? Perhaps the Dolby Cinema presentation might shed some light on the situation, so to speak.

Actually, it was difficult to tell, since the Dolby Cinema version is cropped to 2.20:1. (According to IMDb, that’s the digital-cinema aspect ratio for this movie, not 2.35:1 or 2.40:1.) A hint of those dark areas seemed to be there, but it wasn’t distracting at all. As expected, the black levels were much deeper, and the highlights were brighter. However, the shadow detail was not much better. Also, in some dark shots inside the Moonstone, you can see bright daylight in the background, and it’s almost totally blown out. That’s not the best HDR can do by any means.

Regarding audio, the IMAX presentation is 6.1 with no overheads. That’s too bad, since there are many planes flying “above” the audience. Still, there was some sense of height, since IMAX surrounds are well above the seats, and there’s an extra height speaker behind the screen. Dialog intelligibility was not great overall.

The IMAX levels were quite high: Leq (average RMS level over the entire length of the movie plus trailers) = 105.0 dBZ (flat), 88.9 dBA, 103.8 dBC; Lmax (maximum 1-second RMS level) = 122.6 dBZ; L10 (level exceeded 10% of the time) = 108.8 dBZ; L50 (level exceeded 50% of the time) = 94.3 dBZ. The average was nearly 4 dB above reference level (85 dBA). That isn’t as bad as other movies I’ve measured recently, but it felt brutal because the low frequencies were so high. Usually, there’s about a 10 dB difference between dBC/dBZ and dBA, but it was more like 15 dB in this case because of all the low-frequency energy from explosions and such.

The soundtrack was not mixed in Atmos for the Dolby Cinema presentation. Nolan is known for disdaining lots of channels, so it’s not surprising that he didn’t mix Dunkirk in Atmos. It seemed to me that there was activity in the overhead speakers, especially when planes flew over, so I wonder if the theater was using Dolby Surround to upmix the soundtrack; I’ll try to find out. Dialog intelligibility was better here than in the IMAX presentation.

Also, the levels were more reasonable: Leq (average RMS level over the entire length of the movie plus trailers) = 99.7 dBZ (flat), 85.7 dBA, 98.2 dBC; Lmax (maximum 1-second RMS level) = 118.5 dBZ; L10 (level exceeded 10% of the time) = 103.2 dBZ; L50 (level exceeded 50% of the time) = 89.4 dBZ. Unlike the last few movies I’ve measured in that Dolby Cinema, the average in this case did not significantly exceed reference level.

Dunkirk is being presented in at least six different formats; here they are with the aspect ratio used in each one:

IMAX 70mm film (1.43:1)
70mm film (2.20:1)
35mm film (2.35:1)
IMAX Laser digital (1.43:1 or 1.90:1, depending on screen)
IMAX xenon digital (1.90:1)
Digital cinema, including Dolby Cinema (2.20:1)

Check out this video from Slate.com that illustrates how the aspect ratio and cropping changes for the different formats. Note that this video claims the digital-cinema (DCP) version is 1.85:1, but according to IMDb, it’s 2.20:1. Also, the video does not mention that some IMAX Laser theaters can present the movie in 1.43:1 if they have the right screen for it.

I’m a strong advocate for experiencing content as the creator intended it, and in this case, that’s IMAX 70mm film. In my view, the image quality of film—70mm or otherwise—is not great. It exhibits high black levels, poor shadow detail, judder, and degrading print quality over time, even though the effective resolution is higher than digital. But after seeing Dunkirk in both IMAX 70mm film and Dolby Cinema digital, I must concede that IMAX 70mm film is the way to go here, mostly because of the cropping in the digital version.

To find a theater near you showing Dunkirk in IMAX 70mm or regular 70mm film, check out the ticket page of the movie’s official website.

If there isn’t an IMAX theater showing it in 70mm film near you, the next best option is IMAX Laser, which might be 1.43:1 or, at worst, 1.90:1, and it will almost certainly have better black levels. If that’s not an option, next best is IMAX xenon digital at 1.90:1. Given the choice between regular 70mm film and digital cinema, I would choose digital cinema—especially Dolby Cinema—at 2.20:1. For me, the last choice is 35mm film, which has the most cropping at 2.35:1 and the poor black levels of film.

As I said at the top, I’m not a fan of war movies, so I can’t say I enjoyed Dunkirk. But it’s an amazing story from history, and Christopher Nolan did a remarkable job depicting it. As a cinematic milestone, it’s definitely worth seeing—just be sure to wear earplugs!