How the Shoot Mixed Footage from Open-Gate Alexa and Multiple BMD Pocket Cinema Cameras

Before Ben Davis began shooting Avengers: Age of Ultron, written and directed by Joss Whedon, he sat down with a pencil and paper and meticulously planned out how he'd light the film. "With a floor plan and a pencil in front of me I can light a set very easily, and it's something I quite enjoy doing," says the London-based cinematographer. "But on a film like Avengers there are a multitude of sets that have to be planned, designed and rigged long before you start shooting. With so much else invested in these kinds of productions, when you do a pre-light a few days before shooting, you better make certain it works the way you want it to, and the only way is to figure it all out in advance."

Davis's cinematography credits run the genre gamut, from Layer Cake and The Best Exotic Marigold Hotel to Stardust and Kick-Ass. He also shot last year's wildly successful Guardians of the Galaxy, the perfect Marvel-inspired segue to joining team Whedon for the sequel to the original Avengers, a billion-dollar box office smash when it was released in 2012. "Moving from smaller to bigger budget films, and vice versa, is really not so difficult creatively," Davis admits. "But on these big pictures, like Guardians and Avengers, everything is amplified and becomes much more challenging to manage. As a cinematographer, you want to maintain some sort of creative control over multiple units and crew. That's why a large part of our job these days is done during pre-production."

The newest Avengers, released May 1, had a main unit of three ARRI Alexas. "Although the Alexa was Marvel's preferred camera, we weren't locked into that choice from the start," says Davis. "What wasn't negotiable was the fact that we were shooting digital: that's how Marvel shoots all of its films. So it came down to choosing which I felt was the better camera for the show, since every camera has its own slightly different look. It's almost like choosing a film stock nowadays. You're looking at what the different cameras do and also what they bring to the image. I felt the Alexa was right for this film; I also like the way the camera is built, in terms of practicality on set for everyone involved."

Avengers: Age of Ultron is the first film to shoot ARRIRAW with Alexa's latest Open Gate mode, resulting in a 3.4K output that's more easily upres'd to 4K. "We were a 2.35 production, so we framed within that," he explains. "We wanted to make sure we had as much neg area as we possibly could. In doing that, of course, you're creating a great deal more data to be dealt with later on, which causes different kinds of challenges."

Davis turned to Blackmagic Design's Pocket Cinema Cameras to fill out both the main unit and second unit kit requirements. "I'd been looking at the work Anthony Dod Mantle [Slumdog Millionaire, 127 Hours, 28 Days Later] had been doing with smaller cameras, particularly on some scenes in Rush, which I thought was quite interesting," he says. "The second unit typically needs a fleet of smaller cameras that are less expensive and are rugged enough to handle the various trials by fire, as it were, that we throw at them. To be honest, I looked at GoPros to see what they could do and even some other smaller cameras, but they didn't have a lot of flexibility, and I wasn't particularly happy with the resolution on a lot of them. Having a fixed lens size where I couldn't change the focus or set the exposure wasn't going to work on this film. I wanted far more control."

DIT Peter Marsden (Skyfall, Argo), a friend of Davis's, suggested Davis look at the Pocket Cinema Camera, which he had just purchased. "He began raving about it to me, so I quickly got one in for a test." Director Matthew Vaughn, whom Davis worked with on Layer Cake, Stardust and Kick-Ass, also began using the Pocket Cameras on Kingsman: The Secret Service, which went into production just before Ultron.

During artist tests, Davis brought the first Pocket Camera on set. "I put it through a whole range of comprehensive latitude tests; I wanted to see the quality of the image and I also wanted to see how much information it held in the shadows and highlights," he says. "I was really impressed with what I saw, and that was the fundamental thing we were looking for. I think the Pocket is definitely up there alongside the Red and the Alexa in terms of latitude, and that let me cut in with the Alexa and Canon C500, which we also used, in a much more seamless way. And all that information moves straight on to VFX through grading."

The camera's Super 16 sensor records CinemaDNG raw and, just as importantly to Davis, comes with a Micro Four Thirds lens mount. "Not only could I hold the shot longer than the standard 12-frame cut you typically see, but I could change the lenses and set the exposure exactly where I wanted it to be." Although frame rates for the Pocket Cameras max out at 30 fps, a potential limitation for a film shooting some scenes at 48 fps and on up to 100+ fps, the action scenes shot by the first and second units didn't require high-speed recording. "The majority of the film was shot at standard frame rates, so it was not an issue for us," he says.

Two Pocket Cameras "in their most basic form," says Davis, were part of the main unit and used primarily for the fight sequences. One rotated between a simple 14mm pancake lens and a small zoom. "We rigged the other one in a metal housing, which I researched extensively, so we could PL-mount it. On that we put Zeiss Primes: an 8 mm, 9.5mm, a 12mm and a 16mm."

If an explosion was going off, the Pocket Cameras were placed in and around the explosion. "They were basically in the line of fire, though we weren't that frivolous with them and we never lost one as a result. Personally, I am not a fan of destroying cameras for the sake of the shot. I hate the idea of destroying any equipment!"

The cameras performed robustly throughout the shoot, he adds. "The PL-mounted one could be rigged very quickly to a couple of magic arms to lock it off. We also rigged them to the sides of tanks in some of the scenes, and also on the motorbike driven by Scarlett [Johansson, playing Black Widow] during a chase sequence. That's what I really loved about them: you could literally plonk them down anywhere."

In the film's final act, the Avenger Quinjet does a kind of low-flying strafing run across Thor and Captain America. "I basically took one of the stripped-down Pocket Cameras, put on a wide-angle lens and put it on the ground, set the camera angle with it and let it go," says Davis. "It got thrown up 10 feet in the air, but it was absolutely fine."