Sorry, the s of the ES(s) stands for short back focus, which means that the back lens element protrudes further back into the camera body, it is specifically designed for the smaller sensor of crop sensor DSLR’S, on a FF (full Frame or film) body the mirror is bigger and would hit the lens back element, for this reason the EFs lenses have an extra white mounting index mark and are made in such a way that they will not mount on  a FF body camera.

They wouldn’t have made the cane if you weren’t meant to break the rules