A bevy of 3D movies are making their way to theaters around the world, thanks to simpler and more efficient 3D cameras developed using modern motion-control technology.
For example, a high-resolution stereoscopic camera developed by MSM Design, Hayden Lake, Idaho, uses a motion controller from Galil Motion Control Inc., Rocklin, Calif., to manage film speed and tension so both left and right images stay synchronized.
A 3D movie starts by filming scenes using two different cameras at the same time. Each records the same action from two slightly different angles. When projected, each set of images is sent to one eye of the viewer through a filter. Early 3D systems used a red/blue dye process with separate color filters for each eye. Today, cinematographers typically polarize the two films 90° apart. Special polarized-filter glasses let only images with the proper polarization angle reach the corresponding eye. The brain integrates the two viewing angles into a 3D picture. The advantage with polarization over the red/blue filters is that colors remain true.
The two streams of images must remain tightly coordinated to maintain the 3D effect. 3D cameras from the 50s used bulky mechanical linkages to keep a pair of large cameras synchronized. In contrast, the Gemini 3D camera from MSM does the job using a DMC-2183 eight-axis motor controller from Galil. This lets the Gemini operate with two rolls of film in a single camera similar in size and weight to traditional movie cameras.
The camera’s two film magazines are each controlled by two pairs of axes. A motor in the pair feeds film to the camera while another reels it in. The remaining four axes control motors for the camera shutters, focus, iris, and lens convergence. Power to the motors comes from Galil’s four-axis AMP-20540 500-W and AMP-20440 200-W drives attached to the controller. Electronic gearing between the axes maintains film tensions and position tracking mode for automated and remote focus control. Jog mode ensures precise control of film speed.
The DMC-2183 controller also includes an array that stores parameters for all lenses. Lens change takes only seconds while an automatic data system records and supplies lens calibration info for optimum focus. A menu-driven LCD on the camera and in the remote camera control uses Galil message commands to control the camera while giving the operator complete feedback and set-up information. I/O ports on the controller accommodate direct connection of remote inputs.