The world of animated features is evolving: Dominated for decades by retellings of fairy tales, the last few years have seen Disney's classic hand-painted style updated with computer-generated imagery, and other studios have been muscling their way into the arena. This year, stop-frame claymation steps into the ring with Chicken Run by Aardman Animations, the Academy Award-winning team behind the popular Wallace and Gromit series. DreamWorks and Pathe are co-producers.

Co-directed by Nick Park and Peter Lord (they also hatched the story idea), with the voices of Mel Gibson, Miranda Richardson, and Jane Horrocks, Chicken Run is inspired by war and escape films such as The Great Escape and Stalag 17, and its look is influenced by film noir. Aardman senior director of photography Dave Alex Riddett supervised the lighting and oversaw two directors of photography, Tristan Oliver and Frank Passingham, with John Bradley serving as head gaffer.

Three years in the making, Chicken Run was shot one frame at a time, on as many as 32 sets all running at once. "Basically, we have a very large open studio and we've turned it into a sort of shanty town," says Riddett. "We have movable screens and drapes, because we have to keep changing the size and the shape of our sets. Some are enormous, some are interior rooms which are quite a smaller area." The production's largest setup is 90'x45' (27x14m).

"We have different scales for the characters as well," Riddett continues. "The average size of our chickens is 8-9", but then they interact with the farmer and his wife, who would be much larger. That would be very difficult to animate, so we have a second scale where the chickens are about an inch and a half high. We have the same scene on different scales, and quite often, we have the same set repeated, with four or five versions, all shooting at the same time."

Aardman's hallmark is that it strives for realism as opposed to a cartoony look. "As far as possible we like to treat it as a normal live-action film," says Riddett. "All the same rules apply, in terms of the quality of lighting--you discuss what the mood of the shot is and then try to create it." The film's opening sequence "is played very much in shadows, there's a great sense of mystery about it--you can see characters popping in and out of shadows, you're not quite sure who's there, a lot of things played in silhouette," he says. This involved "a lot of backlighting, and large areas of shadow. Also using a lot of foreground, shooting through barbed wire and fences, which all helps to build the atmosphere, give it a tension."

Also serving to pull the viewer into its farfetched world is Aardman's extensive use of motion control. "In the opening shots we're looking down on what looks to be like a prisoner of war camp, you see these huts all backlit, and immediately the camera starts coming down through the fence, until it finally settles down inside of the compound and we see a figure and a dog in the background. So immediately we're setting up the atmosphere with that camera move, seeing different aspects of it, partly shielded by foreground material."

Aardman has custom-built its own camera heads and tracking units, and uses Mark Roberts Milo cranes (winner of a 1999 technical Oscar) and Mark Roberts Flair motion control computer systems. "They are correct to, I think, 0.1mm over 100 passes, very accurate, and of course for what we do we need that kind of accuracy," comments Bradley, who says that the DP and director "decide upon the amount of move required, that the move is going to be over X number of frames, and then the computer would factor in the ramp-up and ramp-down periods, and the computer will plot that for us."

A sophisticated animated film takes possibly more prep work than a live-action movie. First, the proper cameras needed to be sourced. "We scoured the world trying to find old Mitchell cameras," Riddett explains. "The older cameras are wonderful for us because they are precision mechanical instruments that take one frame at a time very accurately, in fact more accurately than modern cameras because the pin registration system is so good. Basically they're all converted Mitchell BMCs, which we got converted in the States by Doug Fries [of LA-based Fries Engineering], which specializes in Mitchell conversions. And we got video assist attached to them, so that every camera can be fed to a monitor, and we got extra light-proofing put in them, because our cameras are sitting in light for a long, long time, and if there's any light leaks, we're going to get them. So we spent quite a bit of time in research and development of these cameras and getting them made up."

Then there was storyboarding, and computer pre-visualization of scenes complete with motion control. "We actually construct some of the scenes in a computer, and from that we can work out how much set needs to be built, and we can predict what sort of lenses we'll be using," Riddett says. "Because we have so many sets, and we have quite a lot of equipment, it's good to have it planned in advance what sort of lenses we're using, and any sort of camera moves we'll need to have, so the scheduling of the shots becomes very important."

Tests were conducted to figure out how elaborate the sets needed to be in order to convey the proper sense of scale and cinematic scope. "We got away with having the backgrounds much simpler," Riddett explains. "We can actually build a model that goes on forever, in the different scales, but we found that if there's too much detail in there," it no longer looks realistic. "It's better just to have a painted cutout, just a very abstractly painted hillside."

One of the advantages of stop-frame filming is that "we can shoot at any exposure we like," says Riddett. "A lot of our exposure times are like 1/2 second, 1/4 second, so we don't need a massive amount of light. But then we have a disadvantage because our camera position is much closer to the actors, the models. They have very little depth of field, so we tend to stop the lens down as much as possible." The entire movie was shot on Fuji 125ASA tungsten film.

Extensive research took place to find a dimmer and lighting control system that would monitor the voltage in the instruments, keeping the levels consistent over the long periods of time between the single-frame shots taken. "Fluctuation in animation is quite critical," Bradley explains. "With animation you take one frame, and it could be an hour or possibly two hours later by the time the next frame comes, so if the incoming volts for the system were a little high on the first frame and then low on the second, you get a flicker."

Bradley looked at different products from several companies and found that the Strand EC90sv came closest to what was needed, so he approached Strand with a proposal for modifications to the equipment to meet the film's specifications. "One of the criteria was to stabilize the output, which pretty well all the digital dimmers do. The next one was that we needed some sort of automatic alarm system, hence if a lamp had failed or what have you, it would alert the animator so he could call an electrician to sort it out.

"To take away from the animator having to think about too many buttons to push, we wanted to automate the way the lights were controlled," he continues. "One push of the button would turn the work lights down, let it settle, and then we could fire the camera automatically as well. It would then return to the work lights state. Incorporated in that 'button box' is the alarm which would identify any anomalies in the lighting state, so if a lamp had failed, it would sound a buzzer, the animator would stop, and in a worst-case scenario we'd only have one frame to retake."

Strand modifed its EC90 technology "to interface to the lighting control desk and to a camera control unit that would provide a warning if a dimmer reported any change from the previous setup," explains Ed Twentyman, project manager for Strand. "If anything had shut down or wasn't responding, or if the overall parameters had changed, it would prevent the camera from taking the next picture, which is obviously a valuable feature for Aardman.

"What we did then," Twentyman continues, "was repackage the dimmers into a better bitesize chunk, because you don't need hundreds of circuits for every stage, and we produced a cut-down rack in a flight case which could be wheeled around. We also did a customization to record lower-wattage changes, because some of the lights they're using may be part of the set, small light sources, and our bottom threshold of recording changes was about 60W. So we made some instrumentation changes to change the degree of monitoring, and we produced what we called birdie modules." Strand eventually provided one of these custom racks for each mini-set at Aardman's studio.

The camera interface was designed by Aardman, and the alarm interface by Stage Electrics. Strand wrote new software for the EC90 processor to handle these extra facilities, and also contributed GSX consoles with Genius operating software, and Communique application software to connect to external interfaces via MIDI, RS232, DMX, or remote analog inputs to trigger macros. Most of the lighting and grip equipment is also from Strand.

The dimmer R&D process took about a year. "These dimmers have proved to be entirely successful," Bradley declares. "I personally think we've saved thousands of pounds on potential loss of shots, because animators, once they're doing their animation, are very, very focused on what they're doing, and might not notice a lamp at the back of the set gone off.

"Before we used these particular dimmers," Bradley continues, "the electricians would have to go in every 15 minutes or half an hour to physically count the bulbs that are lit, and this caused a distraction to the animator. It can take them a long time to get back into their animation if you keep disturbing them every half-hour; they might not get very much done in a day, so it was very nice to be able to walk away from that side of it and just rely on technology to do the job for you. It was a lot of work in the early stages, and a lot of convincing of DreamWorks that these were worth it, but I personally think they've been very well worth it; they must have paid for themselves 10 times over."

As to lighting equipment, Bradley says, "We don't use HMIs, surprisingly enough. Even despite the high-frequency systems, when you're on long exposures, 2- 3-, 4-, 6-second exposures, you do get a slight flicker with HMI, so all the lights we use are tungsten, except for Kino Flo fluorescents, 4' 2Banks, 4' 4Banks, Micro Flos, and 4" and 6" Mini Flos. The tungsten lights range from 10ks to 650s, then we get down into the low-voltage PAR-16 50W 12V, and also the Altman Micro Ellipse at 50W 12V, so it's quite a substantial range."

This was the first time Aardman had used Kino Flos in a production. "They were quite a new attribute to us," Bradley comments. "They proved to be very nice soft lights. The Micro Flos particularly, being a quarter-inch in diameter, they're very convenient to tuck away, like in the chicken hut, you can put them up in the rafters and it gives a nice, soft, even fill throughout the length of the hut, and yet it's very discreet."

The method of lighting scenes is very similar to live-action setups, but with smaller wattages. "Thinking of one scene I lit earlier in this film, Mr. and Mrs. Tweedy in their office, the key for that was a 2k fresnel, and a similar one in the live-action world would probably be a 12k HMI, possibly a 20k tungsten. We've got a lot of fairly close interiors, the sets may only be 2' wide, so the low-voltage MR-16 lamps would be highlights, pools of light in corners, replicating what a practical would achieve. The PAR-16s or Micro Ellipses you can tuck into the back of a set, hidden behind other props." Riddett says that "because our sets are not full size you can't get the lights in everywhere you want to, so sometimes we'll bounce it off mirrors."

Riddett adds that he used very little camera filtration, but quite a bit of color on the lights for atmosphere. "We tend to use a lot of lavenders and oranges just to warm some of the shots up. And we have sunrise shots that have a nice orange glow. We try to keep our color scheme away from what you'd normally associate with animated films. We find if you've got too bold of colors, you lose the sense of realism we're trying to achieve." Also, since much of the film takes place at night under moonlight, Riddett used cucaloris patterns to give a slight shadowy breakup.

Technical departures for this film from Aardman's previous work are the use of bluescreen and digital pre-grading of the film. A 15'-high (4.5m) bluescreen with an overhanging cove at the top was used for scenes in which the chicken models were rigged for flying. Says Riddett, "It's quite useful, because we can get several angles, straight ahead or looking up. Also we painted it a sort of dark purply blue and use it for the night skies. It's handy to not have to fly the skies, and have something that's permanently in place. The cove is quite an asset."

The production has had the film transferred digitally for the flying rigs to be erased, then put the image back onto film. "CFC, Computer Film Company, is doing our post work," explains Riddett. "One of our big problems we've always had in the past, because the shots take such a long time--sometimes the film will be in the camera for three weeks--quite often we'd get a shot back and there'd be so many little lighting changes, and in fact even the film will change over the period of a week. We'd get very minor fluctuations in the lighting which are so small you can't even correct for them in the laboratory process, but we can correct them a lot easier digitally. Every shot in this film has actually gone through the process of being transferred to digital, and then we do any minor corrections to the lighting there, and also we pre-grade it as well. I was always a purist, but we're not losing the quality of the film at all, and we're gaining a few advantages in our post-production."

"In a lot of ways it's very similar to how we've lit before," Bradley concludes, "but having the slightly different lighting equipment to choose from, it's allowed us to play a bit and experiment in the effects we can achieve. It's been very hard work, but it's been a very good movie to work on and I'll certainly be looking forward to the next one."

Riddett relates, "About two and a half, three years ago now we made up a little sequence, which doesn't actually exist in the film, but it gave us problems of scale, and lighting, and showed us the problems we would encounter. It's about a minute long. I saw it the other day and it looks really crude! It shows how much we've improved since we started."

DreamWorks is scheduled to release Chicken Run in the US on June 23; Pathe and UIP will release the film internationally shortly thereafter.

Directors Peter Lord, Nick Park

Senior director of photography Dave Alex Riddett

Directors of photography Tristan Oliver Frank Passingham

Chief gaffer John Bradley

Technical director Tom Barnes

Strand Lighting R&D team Ivan Myles, general manager Ed Twentyman, project manager David Cusworth, UK sales manager

Lighting equipment Strand Quartet 650W fresnels Strand Prelude 16/30 profile spots Strand Prelude 28/40 profile spots Strand Cantata 1.2kW fresnels Strand Studio 2kW fresnels Strand Pollux 5kW fresnels Strand Vega 10kW fresnels PAR-16s Altman Micro Ellipses Kino Flo 4' 2Banks, 4' 4Banks, 4" and 6" Mini Flos, Micro Flos GAM Products, Lee Filters, and Rosco gel Strand EC90sv 18x2.5kW and 3x5kW custom-modified dimmer racks Strand GSX consoles with Genius and Communique software