PDB said:

So I going through my video on demand (the cable channel Epix in the US) and the copy of ST:ID is 16:9 the whole way through. I'm wondering if someone can rebuild the Imax version from this. Does anyone know which parts of the movie were filmed with the Imax cameras?

The shots where Kirk and Khan are "skydiving" to the other ship in space -- those should be in IMAX. When the movie cuts back to the ships' interiors, these are non-IMAX.

I can't post a screenshot at the moment, but the way to compare whether you're seeing it in IMAX vs. everything being cropped --

When Kirk gets his helmet glass cracked, the camera switches to first-person view inside his helmet. On IMAX, at the top of the frame, you should be able to see the black visor "lip" of his helmet swooping down into the frame across the entire screen -- about an inch above "OFF COURSE". In non-IMAX, we can't see any lip at all -- only glass.