Puggo - Jar Jar's Yoda said:
Ok, that's a great method. So the horizontal stretching factor appears to be about 1.98. That matches the basic definition of 16mm scope being 2x.

Actually it is more like 2.68:1. I was going to say that the reason for the cropping the way it was was due to the way the anamorphic lenses were defined for 16mm, and that may still be true. If the lenses are about 2.68:1, then they would need to crop the top and bottom to match the lens while maintaining the correct aspect ratio, or add black bars to the frame.

Hey, my theory is correct and so is yours. I found this: http://www.film-center.com/scope1.html

So the original frame is 1.33:1 and then it is 2x'd to 2.66:1 which is what we are seeing.