Technique sending two slightly different images to each eye—simulating spatial depth. Works only with active polarization or shutter technology.
Two slightly offset images—one for each eye—create the illusion of depth stratification in the brain. This works because our two eyes are naturally a minimal horizontal distance apart, and therefore each eye captures a slightly different perspective of the world. Stereoscopy utilizes this natural parallax effect, forcing each eye to see its own image—no more, no less.
On set, the work begins with two cameras mounted on an axis—the so-called rig. The distance between the sensors (the "interaxial distance") is crucial: for close-ups, 5–8 cm; for wide shots, it can be up to 30 cm. Too close together, and the 3D effect flattens; too far apart, and viewers get headaches from unnecessary eye convergence. During shooting, you must constantly pay attention to convergence—the point where both optical axes meet. This determines which plane "jumps" out at the audience and which recedes into the background.
In the edit, it becomes complex: both takes must be synchronized frame-accurately, the color balance must be identical, and during conversion to the output format—whether for polarized cinema, shutter glasses, or lenticular displays—new pitfalls constantly arise. Classic errors include depth jumps at cuts, uncontrolled movements out of depth towards the camera ("stereo window violation"), and inconsistent size ratios between the left and right eye, which literally burn into the viewer's eyes. Therefore, every 3D project requires a stereo supervisor who understands the technical context.
The physical limit lies in human vision itself: our brain can only process a depth difference of about 5–6 meters per minute before saturation occurs and the illusion collapses. Anyone shooting in full depth continuously will lose their audience after 20 minutes. Therefore, stereoscopy does not work uniformly—it is a creative tool like lighting or editing, not a mere technical option.