Цитата
1. The plastic mount has been replaced by a metal mount.
2. The focusing ring has been moved back.
3. Two aperture blades have been added bringing the total to seven.
4. Every lens element inside has been coated with Super Spectra Coating for better flare and ghosting resistance.
5. It’s actually smaller than its predecessor at only 1.5-inches.
6. And, last but not least, the STM in the name indicates the Stepping Motor that Canon has added for smooth and silent continuous focusing action.