The Canon RF 800mm F11 IS STM is a fixed-aperture super-telephoto lens for the company's full-frame mirrorless system. Its use of gapless dual-layer diffractive optics allow make it far more compact and lightweight than its EF equivalent. The lens collapses while not in use. The stabilizer reduces shake by up to 4 stops. The lens supports Canon's RF teleconverters (1.4x and 2x) and use autofocus, even at the very small apertures that come along with using the converters.