“Basically, HD shooting has to do with signal-to-noise ratio,” continues Cameron. “In film, photochemical magic takes place in the falloff and in the highlights, but HD reacts very differently — once you start pushing the gain, you have to carefully monitor your signal-to-noise ratio. Our biggest concern was how to deal with the noise in scenes that show Tom and Jamie in the cab, and those scenes comprise about one-third of the movie. We discovered we had to increase the signal — meaning the amount of light — on the actors’ faces to an acceptable IRE level [registered on a waveform monitor], knowing that we’d later bring it down digitally with Power Windows in color correction before the film-out. What looked great to the eye didn’t necessarily translate into a good-looking close-up on the final film-out.

“We therefore found ourselves running a fine line,” he continues. “We’d light beautiful night exteriors that looked amazing and natural and had so much detail, but when we went in for the close-ups, we had to overlight the actors to reduce the noise on their faces. On the monitor, it looked horrible and incredibly overlit. It was very hard to wrap my head around what we were doing, and it went against every instinct I have as a cinematographer. It was a constant battle between what looked good on set and what would look good at the film-out every weekend.”

The filmmakers discovered that any levels below 20 IRE at +3dB or 30 IRE at +6dB on the actors’ faces rendered an unacceptable amount of noise on the projected film image. Respectively, 20 and 30 IRE are roughly equivalent to 2¹⁄3 stops and 1¹⁄2 stops below medium gray (about 55 IRE) on a video signal. According to Cameron, at those gain levels in VideoStream mode, the Viper was actually more sensitive to low ambient light, with less noise, than the CineAlta.

Mann was also insistent about the kind of lighting he wanted for the taxi interior, which Cameron describes as “no light, really. Michael wanted it to feel like ambient light with no specific source. That, coupled with the challenge of filming in a real cab that had little or no room to place any kind of lights, made it incredibly challenging to design an effective plan.”

After investigating many options, Cameron and his chief lighting technician, Phil Walker, chose a new fixture: Electrolumi-nescent Display (ELD) panels. The thin, flexible pieces of plastic encase laminated phosphors and operate much in the same way that Indiglo watches and mobile-telephone displays do. Walker worked with NovaTek, a manufacturer of ELD panels, to custom-create a mixture of phosphors that would provide an acceptable color temperature for the HD cameras. “In the beginning, Michael preferred a warmer color temp, but we eventually settled on a slightly cool green that looked very natural,” recalls Cameron. “That was the easy part. It then took about four weeks to get the panels made, which left us with about a week before principal photography to set them up in the cabs.”

Adding another dimension to the tight timeline was that the production called for four fully functional taxis and three custom-built trailers with various sections of the cab (one for shooting from the front without a windshield, one for shooting through the passenger side, and one for shooting through the driver’s side), which meant there were seven “sets” that had to be rigged with ELD panels.

“The custom trailers were very interesting — we called them ‘Popemobiles,’” says Cameron. “They were basically sliced sections of the cab that were walled in with large panes of Plexiglas that eliminated wind noise yet still let in available light while we were moving. They were constructed on extremely lightweight trailers that got the cars as low to the ground as possible and still had great suspension. The rig gave us a mobile soundstage, which was wonderful.”

Inside the cab, Cameron and Walker wired more than 30 leads in various positions for the ELD panels. Each panel was about 8"x15" and could be placed anywhere and hooked into a lead in just a few seconds. The leads traced back to a custom-built dimmer board, and each panel could be dimmed to nearly 20 percent without any change in color temperature; the device could also run off either a generator or batteries. “You can cut the panels into any shape, but we made most of them in uniform sizes and just cut a few to slip into tight spaces,” says Cameron. “No matter what the size, all of the panels could run from the same lead, so we could switch a 4-by-4-inch panel out for an 8-by-15 and keep the same lead. In the end, we wound up with about 30 ELD panels in each cab.”

About three weeks into the 12-week shooting schedule, creative differences led Mann to replace Cameron with Dion Beebe, ACS (In the Cut, Chicago). Shortly thereafter, Walker voluntarily left the project and was replaced by his best boy, Felix Rivera. “It was one of those situations where we met on a Friday, prepped over the weekend and then started on set on Monday,” recalls Beebe. “Replacing another cameraman was something I’d never done before and would not normally consider doing. Every cinematographer has his or her own identity, sense of working and lighting style, and no one wants to step into a situation where he’s merely there to replicate someone else’s work. When I first spoke to Michael, I was very clear that I didn’t want to come into a situation like that. We met and reviewed a lot of the footage that had already been shot, and Michael said he wanted me to bring my own style to the film. Of course, Michael has a very strong visual sense, and on a Michael Mann film, you’re working very closely with him to realize that.

“Under the lighting plan Paul and Phil developed for the taxi interiors, the ceiling, doors and back panel were covered in a fabric that we could affix the ELD panels to with Velcro, thereby surrounding the actors with light,” continues Beebe. “We had the most difficulty with Jamie because he was wearing glasses, and with the cameras always moving, we were constantly fighting the reflections of the light panels, even when we used non-reflective glasses on him. We ended up adding some Mini Flo fixtures in the cab to get some throw and work around his glasses, because the ELDs fell off pretty quickly.”