Manufacturer description: The new 100-400mm F4.5-5.6 II USM super- telephoto zoom lens features Canon L-series weather resistance and rugged magnesium housing to meet the needs of wildlife and sports photographers or photojournalists working out in the elements. Fully compatible with all EOS cameras, the EF 100-400mm f/4.5-5.6L II USM features a completely redesigned optical formula containing one Fluorite and one Super UD lens element ─ a combination unique to lenses in this focal range ─ to help deliver sharp images with high resolution and contrast. This combination of elements helps thoroughly suppress chromatic aberration throughout the entire zoom range.
The EF 100-400mm f/4.5-5.6L II USM uses a rotation-type zoom ring that allows for more precise adjustments, easier handling, and consistently excellent weight balance during handheld photography. In addition, the lens features an improved zoom torque adjustment ring that allows for the easy setting of zoom tension based on personal shooting preferences. The Canon EF 100-400mm f/4.5-5.6L II USM also features an inner focusing system, a powerful yet quiet Ring USM, a high-speed CPU and optimized auto focus (AF) algorithms for fast and accurate autofocusing in various shooting situations.