Canon Extender RF1.4x

The Extender RF1.4x sits between an RF telephoto and an EOS R body and multiplies the lens focal length by 1.4x, so a 100-300mm f/2.8L reaches 140-420mm f/4 without a lens change. The trade is one stop of maximum aperture, and the optics and coatings are designed to hold chromatic aberration, ghosting, and flare in check across the whole zoom range.

It fits a defined set of RF super-telephotos rather than every lens: the RF100-300mm F2.8L, RF100-400mm, RF100-500mm L, the RF400, RF600, RF800, and RF1200 L primes, and the RF600mm and RF800mm F11 lenses. Dust- and water-resistant construction with a heat-shield exterior coating keeps it working in the field, and autofocus and image stabilization pass through to the camera.