The Canon RF 800mm f/11 IS STM is a unique telephoto prime featuring a distinct mixture of focal length and form factor with Super long reach and super compact design. Its retractable design and a fixed f/11 aperture, this lens's sleek profile makes handheld super-tele shooting a very real possibility, and four stop-effective optical image stabilization further helps to achieve sharp imagery when working in difficult lighting conditions. Gapless dual-layer diffractive optics contribute to a marked reduction in chromatic and spherical aberrations as well as benefit the design of a relatively compact and lightweight lens.  STM stepping motor offers fast, quiet, smooth, and accurate autofocus performance that is ideal for video recording as well as still shooting. This lens is Compatible with optional Extender RF 1.4x and Extender RF 2x teleconverters to further increase the effective focal length. Configurable Control Ring can be used to adjust a variety of exposure settings, including aperture, ISO, and exposure compensation.