Overview

The Canon EF 400mm f/4 DO IS II USM is a lightweight, hand-holdable telephoto lens ideal for sports and wildlife photographers. It offers excellent sharpness across the frame wide open, though not as tack-sharp as the 400mm f/2.8 II. Build quality is professional with weather sealing and improved switch design. Weaknesses include high price and potential sample variation. It suits those prioritizing portability and performance over ultimate sharpness.