Since its release four years ago, the science-fiction/horror thriller 28 Days Later has achieved a degree of cult status for its relentlessly terrifying portrait of a London beset by people infected with a disease that has turned them into crazed zombies intent on tearing the un-afflicted to shreds. Director Danny Boyle and Cinematographer Anthony Dod Mantle shot primarily in the Mini DV format with a Canon XL-1 and finished to film, giving the images a sort of rough-hewn quality and an immediacy that resembled the feeling of events captured on home video by a terrified witness.

Now, 28 Weeks Later begins with an incident set concurrent to the events of the previous film and then propels the story forward some seven months to a point when a contingent of U.S.-led NATO forces has helped contain the uninfected residents just outside London, leaving the city itself to molder with the corpses of the infected who have all starved. Director Juan Carlos Fresnadillo and Cinematographer Enrique Chediak wanted to maintain the overall feel of the first film but also give the sequel its own style, so they opted to shoot the majority of 28 Weeks Later on film in Super 16 format, using video only for specific night vision effects and 35mm film for visual effects elements.

"I love the look of the earlier film," says Chediak, "but we wanted this to be its own movie. We didn't want to do what they did." At the encouragement of the director, Chediak tested Super 16 by shooting scenes and taking them through roughly the same path to film that he would use for 28 Weeks Later. "I really liked the result," he recalls. "Video has great things about it, including mobility, but it does have problems in the whites. By shooting film, I knew I would have a lot more information in the highlights."

Chediak carried two ARRI SR3 cameras and an Aaton A-Minima for the 16mm work. Though the ARRIs had more features, he came to rely on the A-Minima more and more frequently as the ten-week shoot progressed. The cinematographer explains, "The original concept was to alternate between Steadicam and handheld shots, but the director and I really didn't like the feel of Steadicam for this movie, and the A-Minima was great for handheld walk-and-talk scenes. I'd put a wide-angle lens on it, and I'd just know how to follow the actors without really having to hold it in a position where I could look through the viewfinder. I could use a little monitor on top, or not even use it, and I could control it just by watching the actors. It was very freeing."

Chediak wanted to use the slowest stocks possible in 16mm because the grain, naturally, would be magnified when the images were blown up to 35mm for projection, so he went with Kodak Vision2 stocks: 7201 (50D), 7217 (200T) and 7205 (250D). He shot a single scene on 7218 (500T) and then pushed a full stop to get exaggerated grain for a particular effect. For shots that would be more heavily processed in post for compositing or day-for-night effects, he used 35mm equipment--ARRI 435 and ARRICAM Studio--and 5212 (100T) stock.

When Chediak first discussed the film with the director, the two men clicked instantly on the idea of how the attacks by the infected people should look. "We knew it should be very visceral," he says. "I wanted it to be like the camera got infected as well. So it was very shaky, and I would usually shoot with a 45-degree shutter." He explains that since he was using slow stocks because of the small negative, the additional light loss from the narrow shutter angle could sometimes leave him in interiors where he'd be unable to get an exposure. "Those times I would have to tell the director, 'I'm sorry, but I can't give you the 45-degree shutter here."

The staccato effect of the narrow shutter angle would be further enhanced by undercranking to 18fps and then effectively "step printing" the shots in post so, at 24fps, they play back in real time but with a halting, unnatural look to them. These shots were captured with the ARRI SR3s, though, Chediak explans, "If the A-Minima had let me do the 45-degree shutter angle, I would have used it for those shots. The A-Minima is a great camera for fast handheld action."

Chediak notes that a similar effect was created in the first film by altering the shutter speed in the video camera--a process that yields the same kind of movement and sharpness--though the undercranking aspect would not have been possible.

Film was processed at Deluxe in London, and the filmmakers were given basic DVD dailies. The DI work was executed at London's VTR Media Services, with the 35mm film scanned on a Northlight scanner and the rest on a Thomson Spirit 4K. All the material was scanned at 2K resolution, and the color-correction work was done in a Thomson Specter suite. The final 2K files were then filmed out using an ARRILASER film recorder.

Chediak was initially concerned that the full-blown DI suite was not up and running at the time the work was done; instead of seeing the digital files projected, he had to settle for watching them on an HD monitor. "I was disappointed," he recalls, "but when I saw how close the film-out tests really were to what was on the monitor, I knew we would be okay."

Chediak is pleased with the result of the digital post, but he says he continues to be a cinematographer who prefers to get it in the negative wherever possible. "Some people shoot for DI," he says. "They don't do a lot of lighting, and then they create a lot of [Power] Windows later. I like to shoot for what I'm seeing. I try to shoot as though DI did not exist."

And while he appreciates the latitude he was able to get by shooting film rather than video, he warns that it can take patience and precision to get good results shooting 16mm. "In 35mm, you put in some 500 ASA film and push a stop and do wonderful things," he says. "It's much harder to light for 16.

"For us, it required significantly more light and more well planned placement of lights for 16 because, by the time you blow it up, it is less forgiving," he adds. "[Gaffer] Alex Scott and I had to plan exactly for where we could put lights. What rooftops could we get to? Where could I put a Dino or an HMI? Where could we put a Condor? Where could a cherry picker go? When you plan your lighting and execute it very precisely, then you can go crazy with the A-Minima, but you have to light very carefully to be able to do that and make it look good."