The recent resurgence of 3D theatrical movies and the emergence of consumer friendly 3D large screen TVs with 3D Blu-ray DVD players have ramped up the demand for 3D content. Manufacturers releasing economical prosumer 3D cameras and aftermarket dual-camera rigs are either out by this printing or well on the way. Mainstream big budget content like James Cameron's AVATAR has no doubt spurned demand and is selling home 3D systems. Along the way new opportunities for independent video producers will materialize. But there is a catch.

A Little History Lesson

3D movie imaging is just about as old as the invention of motion pictures itself. It may be a surprise to learn much of the still photography of the Civil War was done in 3D. In fact, the first documented public exhibition of a motion picture was L'arrivée d'un Train á La Ciotat shown to a Parisian audience in the late 1800s by the Lumière brothers. Shortly after, it was reshot and projected in 3D!

Hollywood didn't embrace 3D in a big way until the early 1950s, but despite many financial successes, the format all but died out before the 1960s. The point here is that 3D is nothing new. What is new is the affordable technology to make good 3D video and get it to the consumer's eyes. This is not about the dual-color anaglyphic (red and blue filtered paper spectacles) process that only works on monochromatic images.

2D or Not 2D

Which brings us to the issue of monitoring. Top of the line 3D camera systems are very expensive and either come with or have access to in-field 3D monitoring. These high-end systems are not the subject of this article. Most of the semi-professional 3D cameras are reasonably priced, somewhat restricting and they rarely have an on-camera ability to display a 3D image to the camera operator. Consumer grade cameras are even less accommodating. So what to do?

In the past, a steady diet of experience in the form of trial and error led to skilled technicians who could be counted on to bring home good 3D scenes. The early 1950s 3D films like Bwana Devil and House of Wax were shot with very heavy dual 35mm camera rigs and were impossible to monitor in 3D. Even Creature From the Black Lagoon was expertly shot in 3D underwater without any means to monitor the images recorded on film. Then, in the late 1960s, Chris Condon invented a single camera and projection system called Magnavision (later known as StereoVision) that made 3D filmmaking efficient and economical. The system placed the left and right images side-by-side in the same negative four perforation space as conventional single strip motion picture production. The system used common conventional film cameras and a single projector in the theater. With his newly invented system, Chris produced The Stewardesses that ran in theaters around the world for months and grossed almost $30-million in 1970. The only way to monitor the 3D quality back then was to shoot the film and screen it the next day in a 3D screening theater (dailies). But, even Chris couldn't check his images in 3D at the time of shooting.

Here and Now

Today there are several ways to check and confirm your 3D images while shooting. Why is this important? Well, for one thing, the nature of the 3D effect is not readily apparent in a 2D viewfinder or monitor. By experience, a videographer can learn to shoot and compare the left and right images in a superimposed monitor and pretty much come to realize what the end product will look like. A camera (or lens) that has an adjustable interocular control can set the ideal dimension position of the subject/object in the frame. Always remember the most pleasing 3D emulates the human perception experience. This means most subject/objects should be positioned unnaturally close to the 3D taking lens and the lens should be wide angle. Most shooters new to 3D often make the mistake of framing with longer lenses and focusing on subjects too far from the camera mainly because they can't see the 3D image until much later. Even so, ESPN has been experimenting with long-lens sports coverage in 3D. At first glance this would seem to be an oxymoron since we humans don't see with telescopic eyes.

Mark Cholis at Grass Valley says that "many of the productions that use our Kayenne or Kalypso production switchers for live 3D events will have a single 3D monitor in the truck for the director and TD to work from, another for the Stereographer and then strategically place one outside the truck to help keep unnecessary foot traffic and interruptions down while doing the production."

Some 3D camera systems feature dual viewfinders, one for the left eye camera and one for the right eye camera. On-camera or aftermarket binocular-finders work well and can easily be viewed during daylight shooting. However, these types of finders may not be particularly useful when using cameras that are preset at the factory for intraocular convergence. (Interocular refers to the distance between human eyes, about 2.5 inches.) More elaborate dual camera systems offer a flexible adjustment for interocular convergence. Having variable convergence is desirable when the 3D is to be "pushed" for effect. That said, it is possible to adjust convergence somewhat in post production, which will be addressed later. An adaptation is dual video spectacles that optically deliver the viewer a 3D image in a heads-up display that can be wired to emulate 3D. These presently are not HD capable to the consumer but can serve the purpose. By the time you read this, consumer HD versions may be commercially available.

The other way to monitor 3D is with electronic liquid crystal shuttered eyeglasses and a dual feed SD video alternating field interlace accessory. There are numerous incantations of this process and demands research as to what is currently available. These devices have been around for more than 20 years. They take discrete video feeds from the two camera sources and alternate the left and right images between field one and field two in standard definition NTSC. The new 3D Blu-ray TVs use a descendent of this technology. This method may be used to confirm your 3D in SD is on point for the audience even if you're shooting HD but seeing 2D. The main drawback to this technique is observing the monitor on location in daylight. This can be somewhat overcome by shading or tenting the monitor. Of course this also requires electronic liquid crystal shuttered eyeglasses that either run on batteries or are cabled to the interlace device. Fortunately there are some new systems available for this purpose that are reasonably priced.