Imax Projectors - The Fallen Leave Effect

i remember seing a documentary bout imax when it was first developed. They could not get any mechanism which could move 70 millimeter film on its side fast enough. And no matter what they tried, it always ended up creating what they called the autumn leaves effect. But e yet, imax had a squarer aspect ratio of about one point four to one. So that the full imax experience, filling the whole height of the screen is coming very close to that academy ratio again.