The RF 70-200mm is the first pro-grade zoom of its focal length and aperture to sport a collapsing design. It's much shorter, just 5.8 inches long, at 70mm than at 200mm (8.2 inches), so it's Canon's current 70-200mm options: (left) the RF 70-200mm F2.8 L IS USM and (right) the RF 70-200mm F4 L IS USM. The second major lens to prove the concept was the hugely popular Canon EF 24-105mm F4L introduced in 2005. IfwY.