Spectrometer Makes Filmmakers See Red

Dan Drollette

Cinematographers hate fluorescent lights. Although these light sources look more or less normal to the human eye, they show up as green on film. Worse, they impart a weird and unhealthy greenish cast to everything they illuminate, including human flesh tones. While oddball hues may not seriously affect someone's Christmas snapshots, they are a major problem for big Hollywood film productions. (A director can't have Michelle Pfeiffer's skin look green in a love scene.)

It gets worse

To compound the problem, fluorescent tubes shift in color as they age, and some scenes involve multiple lighting sources -- such as mercury vapor lights or sodium vapor lights -- that operate at different color temperatures. Color meters have trouble reading these complexities, making it difficult to know what filters to put on the camera to compensate.

Color films see light differently than the human eye does.

In American Cinematographer in June 1996, cinematographer Victor Kemper described one such lighting situation on the set of the film Eddie as "astonishingly scary. ... The lights were generating green spikes in such odd places that I was wondering if there was a solution."

Fancy digital software can fix this in postproduction, but the costs are exorbitant. Filmmakers stuck in such situations appeared doomed to spending lots of money on multiple takes involving different film stocks and filter combinations -- until Eastman Kodak scientist Mitch Bogdanowicz helped move things to the red end of the spectrum.

With an S2000 miniature fiber optic spectrometer manufactured by Ocean Optics Inc. and a laptop computer, Bogdanowicz arrives on location to solve lighting problems. The equipment allows him to take readings at a higher degree of accuracy than standard color meters, which work only with light sources that give off a continuous, even, broad illumination. He said the small size, light weight and portability of the outfit are major pluses in the motion picture industry, where it is important for the technical support to fade into the background.

On the Eddie set, Bogdanowicz's computer program plotted a curve, and he suggested the addition of a specific blue gel on each light and a correction for green on the camera lens. "That was exactly right," said Kemper.

Bogdanowicz has been called in on several Hollywood shoots since and was given an Academy Award last February for technical achievement for his work on color control in motion picture lighting.

He said he has run into a number of actors and actresses but has not been able to ask for autographs.