Polygon: Superman’s most amazing special effect didn’t require computers or a green screen
The amazing part of this performance is how clearly you can see Christopher Reeve shift his body from Clark Kent to Superman. His voice changes a bit, sure, but it’s all there in the body language. It’s a powerful, physical performance that doesn’t require a change into the costume or any of the special effects that went into the flying scene.
It’s amazing to see this change in isolation. Christopher Reeves appears to physically shrink the moment he withdraws back into the identity of Clark Kent. A later scene that shows the opposite transition is just as striking.
I’m one of the few who actually likes Man of Steel, and I enjoy Henry Cavill’s portrayal of Superman, but this is something he’s missing. He just doesn’t sell Clark Kent the way Christopher Reeves could.