The Avengers Conquer Digital Workflows with ARRI ALEXA

DP Seamus Garvey and second unit VFX photographer Jake Morrison, both first-time ALEXA
shooters, describe camera testing and on-set workflows for ‘The Avengers’.

Cinematographer Seamus McGarvey, ASC, BSC, has pursued naturalistic looks for his previous films including ‘The Soloist’, ‘Atonement’ and ‘Nowhere Boy’. His latest work with director Joss Whedon on his superhero blockbuster, ‘The Avengers’, represents a contrast. The movis stars a mighty coalition of Marvel comic book characters Iron Man, Captain America, Hulk, Thor, Black Widow and Hawkeye battling evil forces, and includes abundant visual effects and CG environments.
Digital Debut Seamus said, "I was quite excited by the prospect of doing a film that would expand my horizons in terms of learning about visual effects on such a grand scale. I knew I would be employing a different cinematographic approach to a film like this." ‘The Avengers’ is his first digital project, which he shot on the ARRI ALEXA system. "I had never tried to shoot or test a digital camera before, so for me it was a leap into the dark," he explained. Among the first comparison tests he made with the camera were for lowlight conditions, shooting under candlelight and bracketing the exposures. He was impressed by how far he could take the ALEXA before the image would start to break up. ALEXA's base sensitivity of EI 800 and latitude of 14 stops were useful in low light and night shoots done for the movie. "The camera came into its own in those conditions, working just on the cusp of daylight and into night, where I was dependent on ambient lighting as well as conventional lighting," said Seamus.
VFX Testing Because of the high number of both interior and exterior visual effects shots, extensive testing was done for these as well. "We were going to shoot sometimes on a very large scale in situations where I couldn't control the ambient spill of daylight," he said. "I would have greenscreen lit with hard sun and shade at the same time, within the same shot. One of the first tests I did was to see the tolerance of various camera systems in terms of latitude and ability to extract a key from blue and greenscreen in those ambient lighting conditions. The ALEXA had more range and produced a cleaner key in all conditions." The tests convinced Seamus the camera would be able to produce  the images he wanted, and he actually purchased one of the first ALEXA Plus models in time for production and named it Schatzi de Bayer, which he recently upgraded  to handle slow motion. The complete camera package on ‘The AVENGERS’ consisted of four ALEXAS and an ARRIFLEX 435 for high speed shooting, because higher frame rates were not available on ALEXA at the time of the shoot.
Codex-ARRIRAW Workflow Seamus also conducted detailed tests with the ARRIRAW to Codex ARRIRAW recorders workflow during pre-production, when the ALEXA again showed an extended range and produced a clean key in most conditions. Shooting ARRIRAW to Codex also allowed greater flexibility in post with uncompressed 12 bit logarithmic files, and he found that, overall, the workflow made the transition to digital fairly straightforward. On set, production DIT Danny Hernandez managed four Codex Onboard Recorders on his cart. Along with the media from the cameras, he recorded colour decision list values to the recorders. Seamus supervised colour applications on set and the looks he established were passed to Efilm in Los Angeles, the post facility handling dailies processing and final digital intermediate work. Colour timing took place there with colourist Steve Scott. The clean-looking images with abundant information gave them plenty of scope to work with, straightaway. Editorial was located near-set and was equipped with a Codex Digital Lab. Editorial crew checked and corrected the metadata, and made back-up copies of the ARRIRAW files to LTO-5 tape. The data-packs from the Codex recorders were then sent to Efilm for dailies processing. Bruce Markoe, SVP Post Production of Marvel Studios said he felt that using the Codex Digital Lab in editorial helped speed up dailies processing, and also the visual effects preparation. “Visual effects utility shots such as tiling and colour charts were restored from LTO-5 tape using an EDL and quickly sent to the appropriate visual effects facilities, which saved time and money," he said.
Shot Composition The director and DP developed their visual approach together and were aiming for an instinctive, naturalistic quality in the images. "We wanted this to feel immersive and did not want a 'comic book look' that might distance an audience from engagement with the film. We moved the camera a lot on Steadicam, cranes and on dollies to create kinetic images, and we chose dramatic angles, such as low angles for heroic imagery." The frame was composed for the 1.85:1 aspect ratio, a concept Joss put forward early on. Seamus explained, "Shooting 1.85:1 is a little unusual for an epic film like this, but we needed the height in the screen to be able to frame in all the characters like Hulk, Captain America and Black Widow, who is much smaller. We had to give them all precedence and width within the frame. Also, Joss knew the final battle sequence was going to be the extravaganza in Manhattan, so the height and vertical scale of the buildings was going to be really important." For the climactic Manhattan street battle sequence, the film crew shot inside an abandoned factory in Albuquerque, New Mexico, where a very large set had been built combined with a greenscreen background. Shots of Grand Central Station were later composited into the background of these scenes, which needed to feel like an exterior daylight sequence. "We bounced about 40 ARRI 18K ARRIMAXes up into white UltraBounces in the ceiling to produce our ambient light. I used 8'x8' Mylar mirrors with 18Ks spotted up into them to produce hard light kicking off glass buildings. It allowed us to work uninterrupted while it rained or blew a gale outside. For the amount of action that takes place in the movie, it produced amazing consistency in lighting terms."
Greenscreen/Bluescreen Jake Morrison was hired as a VFX supervisor for Marvel to manage second unit for ‘The Avengers’, shooting aerial photography and background plates, and work with the main visual effects supervisor Janek Sirrs. Jake’s previous film credits include ‘Iron Man 2’, ‘Thor’ and ‘300’. Like DP Seamus McGarvey, the project was also his first chance to work with the ALEXA camera system. He said, "The ALEXA is the first digital camera that has a film-like response. To me, it's a big difference from the other cameras I have worked with." One of the logistical challenges on the production was dealing with the large number of main characters and the specific needs each actor had regarding blue or greenscreen. Black Widow has red hair, Thor is blond and Captain America's costume is close to the chroma blue colour. Keying the ALEXA ARRIRAW footage brought certain advantages, according to Jake. "The response particularly to green and blue by ALEXA was very good. There are a lot of benefits to digital. You haven't got gate weave or grain structure and it allows you to get more fine detail from hair, edges and better extraction of motion blur."
Aerial Environment Shoots For scenes taking place in Manhattan, Jake’s team shot aerial footage over three days for use as background plates. "I focus on getting as much aerial work in as possible for the audience to see the big expanses, the wide establishing shots, while also making sure that the effects work doesn't look too computer generated," he said. "We're getting much better at making entirely CG environments, but there is no substitute for starting with a real image and adding what you need." During the city shoots, Jake especially noticed ALEXA's image quality after dark. "I'm very familiar with film stocks and you know what you can get away with at night, but ALEXA loves the night. With a good DIT set up, you can get a very rich digital negative with lots of information to work with in post, but still have dailies that look really good - sharp, contrasty and punchy." ALEXA has a 3.5K sensor to allow high sensitivity and a wide exposure index to produce its particular look. As higher resolutions become available now, Jake still recommends assessing overall camera performance, and said, "I'd rather have better pixels than more pixels. Some cameras capture more pixels than ALEXA, but given the choice of that or having latitude and better image sampling, I'd much rather have the latitude. A more grain-less structure with a sharper, cleaner image is more important to me."  www.arri.com