Comment by shawa_a_a

This isn’t exactly the case. The camera has an actuating mirror on the end of the rotating arm that allows it to point at arbitrary angles.

https://youtu.be/aXfTgCCsRSg (T=4:30)

The emulating different lenses part is that with this setup you can parametrically collect specific rays bouncing off the object (presumably the angle of the mirror with respect to radius), and the resulting image will be the same as you’d get from a lens with those parameters.