Every once in a while an opera production comes along that makes the audience sit up and look as well as listen. This season's revival of Wagner's Tristan und Isolde at the Metropolitan Opera falls into this category, with sets and costumes by Jurgen Rose and lighting by Max Keller every bit as compelling as the commanding singing by Ben Heppner and Jane Eaglen in the title roles.

Making his Met debut, Keller brings along a quarter-century of experience as head of lighting at the Kammerspiele in Munich, Germany. He has also designed for opera houses around the world, but prefers not to be fully freelance. "I like having the Kammerspiele as my headquarters," he said at Lincoln Center during a break from rehearsals at the Met. "I can work with the in-house electricians on technical innovations."

This kind of tinkering was apparent in Keller's choice of lighting equipment for Tristan und Isolde. The production is set in a modern, geometric tensile structure (basically, a large white tent), while the costumes have a more timeless, fantasy feeling to them. Scattered props and set pieces rise from traps in the stage throughout the evening, but the tent is the primary focus. "We felt the most important thing is the story," says Keller. "There is an almost minimal approach to the scenery and more emphasis on the lighting."

To light the expansive white surfaces of the set, Keller designed a rig that when seen from backstage looks more like a complicated film shoot than an opera set. As the show opens, a ship moves into place for the first scene. The lights, dimmers, and ballasts move with the ship as it slides 20' (6m) downstage. The tent, made of white cotton fabric from Gerriets, is preset 20' upstage of its playing position and moves slowly downstage along with the ship on a steeply raked wagon. The fabric is stretched over aircraft cables to hold it taut, and tied to aluminum trussing with bungee cords.

This aluminum truss was custom-built in the shop at the Met. It forms a rectangle to support the portal, or downstage end of the tent. Above the tent, a triangular frame stretches upstage to hold up the front truss and support lighting equipment behind the fabric. All the light is bounce light reflected onto the white surfaces of the tent from white canvas flats on the sides and overhead. "This is like a turn-of-the-century lighting technique used in Europe," notes Keller. He used this indirect lighting to ensure even washes of color on the fabric.

"The color temperature is very important in this production," he says. To achieve the cool to cold tones of blue and white he desired, Keller used large HMI fixtures. "The stage at the Met is huge--I needed a lot of power in the lights. The HMIs are four times brighter than tungsten."

To get the power he needed, Keller used 20 Arri Compact 4kW theatre fresnels with 12" lenses (purchased by the Met for this production) and fitted with Licht Technik "Darth Vader" dimming shutters and Mag Max 350 color scrollers. These were the workhorses for the production and hung on the truss behind the tent, along with nine Mole-Richardson 5kW fresnels with red gel (R26 Light Red). "Red gel in front of the HMIs doesn't give me the blood red I want," explains Keller. "It's too blue."

Color plays an important role throughout, with the fabric panels changing hue as the emotions, locations, and times within the production change. Blue represents a dark night, white is for day, yellow announces the king's arrival, and the red is for love. "Other characters also have distinct colors," Keller notes. "These colors stay constant for each character throughout."

One of the most dramatic color shifts is that to red as the lovers drink a magic potion. The entire tent turns a deep red for about 10 seconds, with the singers silhouetted against it. Then the light fades back to a cupid's pink, then to the white daylight mode. "The light enhances the action," says Keller, who uses this color-coded design style to convey emotion or explain a situation. "Singular colors are used for their psychological effect--red can also mean war."

The lighting rig also contains two Robert Juliat 2.5kW profile spots with color correction in front-of-house positions, where there are also 10 ETC Source Four 5-degree and 19-degree ellipsoidals as well as a Pani BP6 Gold projector (used for a dark blue wash of the deck). Four Juliat 1kW zoom profiles and another 23 Source Fours are hung on the tormentor towers, while in the side galleries there are two Arri 4kW HMIs with Wybron color scrollers, four Arri 1.2kW HMI PARs, five 10-degree Source Fours, and four lkW Strand 6x16 lekos.

On the first lighting bridge are two Arri 1.2kW HMI PARs, three 1kW Altman 6x16s, and two 1kW Strand 6x14s. Sitting in the prompt box is a Mole-Richardson 650W nook light to provide a downstage uplight to reinforce a burning fire. Built into the Act II watchtower are two Strand lkW asymmetric floods, one Lighting & Electronics MR-16 Mini-Strip, and two Altman 6" 750W fresnels.

To add to the color intensity on the tent, there are also 22 four-circuit dimmable 240V fluorescent cyc units (built by the Met and DMX-controlled) and 24 Strand Iris 4 cyc units. Two additional Arri 4kW theatre fresnels are also standing on the floor to reinforce the intensity along the bottom of the tent.

This kind of rig is unusual for the Met in two ways: It is very small, and Keller put instruments in unconventional positions. "It is not the number of lights that is important," he says, "it's how you use them. The HMIs are so powerful you don't need much more. They create the atmosphere." The cold HMI light is mixed with the followspots ("You have to do that in opera") and with warmer tungsten for additional side- and frontlight.

"There is no direct lighting on the tent," he continues. "By bouncing the light off a reflective surface, I can control the exact shapes and have very sharp separations between the colors with no bleed. This show is very abstract scenically and depends on the light."

Some of the color changes are slow crossfades, lasting up to 10 minutes. "You can see the color coming," says Keller, who has one 20-minute cue of blue washes creeping slowly onto the fabric. "It is very smooth and flat, not a real color shift." His palette includes cool blues, cold, almost surreal whites, and saturated shades such as the blood red as well as a chrome yellow.

In the color scrollers, Keller used R00 (Clear) and R97 (Light Grey), while in the Mag Max 350s he added R312 (Canary) and R385 (Royal Blue). The color for the Arri HMIs included both the royal blue and R80 (Primary Blue). Other colors ranged from R367 (Slate Blue) to R65 (Daylight Blue).

During the run of Tristan und Isolde, this complicated lighting rig had to be dismantled almost daily to accommodate the repertory schedule. "It takes two hours to break down and two hours to rebuild once the set is in place," says Wayne Chouinard, resident lighting designer at the Met, who was responsible for the lighting once Keller returned to Munich.

Interestingly enough, this kind of production allows the storyline and singing to come through loud and clear, unencumbered by unnecessary elements. "This is a new way to see this opera," says Keller, whose lighting created a series of dazzling tableaux to frame Wagner's star-crossed lovers.