Panavision (Super35) became popular from 90s.
As a matter of fact, photography directors set the camera originally for 2.39 theatrical picture with consistent coordinates on camera.
This images from T2, explaining how the Super35 process works.
This is the finest upconverted 3D film I have ever watched, specifically for new aspect ratio.
Here's an overview of the new and prevsiously formats:
new 3D version - 16:9
2.39 version (it seems that we have less picture in 2.39 than 16:9)
classic 4:3 version from TV
and new leaked shot...