Canon EF 400mm f/5.6L USM

The Canon EF 400mm f/5.6L USM is a legendary telephoto lens prized by bird and wildlife photographers for its exceptional sharpness, lightweight design, and rapid USM autofocus. Unlike its RF counterpart, this EF version requires an adapter for mirrorless cameras, adding length and weight. While there is no direct RF 400mm f/5.6L USM equivalent yet, Canon's RF telephoto options offer improved image stabilization (not present in the EF version), better weather sealing, and updated optics, though many professionals still cherish the EF version for its robust build and precise focusing capabilities.