which sets the convergence around the subject at the time the switch is pressed. There is no "homing" function with this switch and once adjusted, the convergence remains at this setting until reset. The camera operator is free, however, to change convergence manually while the XLI is running. Closest focusing distance of the 3-D lens is 3.3 feet.
           The stereoscopic lens, like the XLI, is made of a light and durable magnesium alloy and weighs 35.3 ounces, is 5 1/2 inches long overall, includes a hood, has a filter diameter of 52mm and an effective image size of 4.8 x 3.6mm. One filter only can be used at a time with the 3-D lens which does not have a built-in neutral density (ND) filter and, owing to lens structure, polarizing filters cannot be used with it. An ND filter can be mounted to the filter screw on the front of the lens.
           Canon developed the 3-D lens to support emerging markets for stereoscopic imagery in entertainment, marketing, education, medicine, architecture, product design and fashion. Though the 3-D lens won't be available on the market until October, several prototypes have been in use for the past few months. Jason Goodman, a DP and Director with his company Multimedia Software Design in New York, used the 3-D lens with the Canon XLI to produce two stereoscopic trade show presentations for a client of the company. "We've done two corporate videos in 3-D for a company called Broan-NuTone, which manufactures various items for the home including ventilation systems and intercoms," says Goodman. "They wanted to create a 3-D video to be played at a Virtual Reality theatre at the International

Builder's Show in Atlanta, Georgia last February. The first video we did was called 'Enter a Nu Dimension' and shows a young, married couple going into a home and covers all the features and benefits of Broan-NuTone products."
           The Virtual Reality theatre at the trade show consisted of 16 seats equipped with a rumble sound system. The audience wore HMDs from IO Display Systems for viewing the 3-D video. The IO Display HMDs feature a personal stereo sound system and are wired to a single playback unit running the 3-D video. IO Display markets a number of HMDs ranging in price from $499 to to $699 and a typical pair weigh about 8 ounces, use S-video or RCA video input and don't have the flicker associated with alternating field playback.
           "Resolution of the IO Display was about 320 x 240 pixels," says Goodman, "but what is nice is that it is a pretty immersive experience and gives a very satisfying 3-D image. We are the first company in the US to do an actual shoot with the 3-D lens and we had specified use of the IO Display HMD." In addition, Goodman used the IO Display HMD while videotaping for 3-D playback and real time 3-D viewing for set-ups and camera rehearsals during the shoot. "We had a Eurojib there and were subtly moving the camera," says Goodman. "We tried to get a continuous perspective change going

and kept things moving in relation to one another within the shot. That was very effective." Lighting for 3-D, as Goodman learned, is somewhat different.
           "We needed a lot of light. I told the gaffer to figure the light for a standard video shoot and then double it. So, we had a bunch of 4Ks and HMIs. We were shooting in a house in Wisconsin during the winter and I had the gaffer go in the house and light up the back room. He looked at me like I was crazy, but I wanted a lot of depth of field in the house. When the door opens in the shot, you see into the depths of the house. It worked great. We did a lot of lighting for things you might not normally light on a video shoot so we could have detail in multiple planes of the image."
           The second 3-D video, "Fresh Ideas Inspired by Dreams," loosely inspired by "Alice in Wonderland," was all about kitchens and was shot on a set. In a dream, a woman is transported to her ideal fantasy kitchen. "There is a hidden range in one of these wonderful kitchens," says Goodman. "We got as close as we could, but we had to match up a 3-D model of the range hood with the real range hood in the kitchen. So we moved seamlessly from a live action 3-D shot into a CG 3-D shot of the kitchen and then up into the range hood."
           In general, Goodman made conservative use of the convergence adjustment feature on the 3-D lens. "I tend to think the best thing to do is to make the shot as comfortable for the viewer to see as possible. I relied on a lot of other monocular depth cues to get the 3-D to really work and generally was converging on