The sensors are a few SMD packages on a flat-flex and the motor is a voice coil with a few dozen winds of fine enamelled wire. The mounting system for the stabi

The sensors are a few SMD packages on a flat-flex and the motor is a voice coil with a few dozen winds of fine enamelled wire. The mounting system for the stabilized element is marginally more complex, but you're only moving one small element out of the dozen or so elements in a modern prime or the two dozen in a good modern zoom. It's pretty negligible, and it's becoming irrelevant as the industry moves to body-based stabilization. The Canon 50mm f/1.4 weighs 290g. It has seven elements and acceptable optical performance. The Sigma 50mm f/1.4 Art weighs 815g. Same focal length, same sensor coverage, same maximum aperture, same focus motor technology, but it has thirteen elements and vastly superior optical performance. More and bigger elements are necessary for a better lens, but big lumps of glass are heavy. There's no getting around that.