The Canon EF 200-400mm f/4L IS USM EXTENDER 1.4x lens with built-in 1.4x focal length extender
Fiddling with lenses and focal length extenders to get the effects we want is an annoying necessity for photographers – but the latest announcement from Canon has the potential to make all the company's lenses at least twice as useful. The Canon EF 200-400mm f/4L IS USM EXTENDER 1.4x is the first lens Canon has made with a built-in focal length extender. At the flick of a switch, it goes from 200-400mm to 280-560mm while maintaining its presumably stellar L series optics through the whole zoom range. That's one less fiddly lens change for wildlife and sports photographers, and one heck of a great idea!