Large-format 3D projection system with dual 15/70mm film strips — polarizing glasses and dual projection create stereo depth. Highest optical sharpness and brightness in commercial cinema.
When shooting for IMAX 3D, you're working with camera logistics that fundamentally differ from standard productions. You need two 15/70mm film cameras that are precisely synchronized — one for each eye. The distance between the lenses determines the stereo base and thus the sense of depth. Incorrect calibration not only leads to uncomfortable viewing experiences but also headaches for the audience. The lenses must be adjusted perpendicularly to each other to the millimeter; any deviation will be visible on the seven-meter-wide screen.
The system uses circular polarization instead of linear — which is why you can move your head in the cinema without the 3D effect collapsing. Each camera exposes its film strip separately, and both run synchronously during projection. The image area utilizes the full 15/70mm format (eight perforations high instead of the standard four), giving you an optical resolution that forces you as a DoP to think: every imperfection on set becomes visible. Dust on the lens? You'll see it at the nearest IMAX cinema — in massive magnification.
Practically, this means: edit lists become complex. You coordinate two parallel negatives, and the editor must keep both strips synchronized to the millimeter. The lighting setup effort doubles because both cameras require identical lighting but shoot from slightly offset positions. Parallax effects arise quickly — where the 2D eye is relaxed, IMAX 3D sometimes creates optical tension that you must control.
The luminance in the cinema hall is impressive, but that's also the biggest challenge: the system tolerates no underexposure. Your approach must be conservative — rather a stop too bright than too dark. High-contrast scenes lead to flicker effects through the polarized glasses. For moving objects: rapid camera movements can create optical artifacts in an IMAX 3D auditorium that are not noticeable in the rough cut but are distracting in the finished film. Therefore, many IMAX 3D productions (see also keyword Stereo Cinematography) are choreographed more statically — this is not a deficiency but a design principle.