With a Ring USM Drive, Dual Power Drive, high-speed CPU and optimized AF algorithm, these lenses are claimed to provide fast, yet quiet autofocusing.

Even with all of these extra optics in these lenses, Canon has managed to reduce the focusing distances to 2.6m for the RF 800mm f/5.6L IS USM, which is less than half the distance of other 800mm f/5.6 lenses, ASC coatings are used in conjunction with the improved lens design to minimize ghosting and flare. The lenses feature Fluorite, Super UD and UD elements. Steps, this allows for smoother transitions between aperture changes when shooting video. The RF 800mm f/5.6L IS USM provides up to 4.5 stops and the RF 1200mm f/8L IS USM up to 4 stops.Д«oth models feature a 9-blade circular aperture that can move in 1/8th Optical PerformanceД«oth the RF 800mm f/5.6L IS USM and RF 1200mm f/8L IS USM work with Image Stabilization. The RF 1200mm f/8L IS USM just 3.34kg which makes it more than 13kgs lighter and 30cm smaller than its legendary predecessor the EF 1200mm f/5.6L USM. The RF 800mm f/5.6L IS USM is CanonвЂ™s lightest and shortest 800mm L-series lens and it tips the scales at 3.1kg. They are both significantly smaller in size from their EF counterparts.

According to canon, the newly designed optical system enables them to achieve these long focal lengths in a design that is smaller and lighter in weight than traditional super-telephoto lenses.

Cenon 1200