Also contributing to the reduced size of the Canon RF 800mm F11 is a distinct optical layout, which uses gapless dual-layer diffractive optics instead of multiple heavier individual elements, which also effectively controls color fringing and chromatic aberrations for high clarity. Complementing this design is an STM stepping motor that delivers quick and quiet autofocus performance that is suitable for both stills and video needs. Additionally, a Control Ring is also integrated into the lens design for intuitive control over exposure settings from the lens itself. If you decide you need more than 800mm, this lens is compatible with the 1.4x and 2x RF Extenders for an equivalent focal length of 1120mm or 1600mm, respectively.