Hmmm … its a 2D Arri Alexa camera with two small 2K cameras, one on either side of the main camera. Does it shoot 3D? Not exactly. The two extra cameras are used to capture depth information for later post processing and conversion of the original 2D video into a converted 3D representation.
The advantage of doing 3D this way – versus shooting true 3D to start with – is that in post production you can create some 3D depth perspectives that are difficult to do in true stereoscopic 3D shooting. As I mentioned previously, the 3D conversion of Top Gun had a few scenes featuring good 3D depth from near to quite distant – which is difficult to do with a paired camera. (The lens spacing needs to be narrow for close in shots, but narrow spacing reduces the depth effect as you move further away from the camera).