Compact Canon 400mm f/4 using diffractive optics for dramatically reduced size and weight.
The Canon EF 400mm f/4 DO IS USM is a compact super-telephoto featuring Canon's diffractive optics technology that dramatically reduces size and weight compared to conventional 400mm designs. The DO element enables a lens nearly half the length of a standard 400mm f/4, making it uniquely portable for super-telephoto wildlife and sports photography.
Optical quality is good with the DO element providing compact dimensions while maintaining respectable sharpness. The IS system delivers approximately two stops of stabilisation. The ring-type USM autofocus provides fast, accurate focusing for tracking moving subjects. The f/4 aperture offers good light gathering at 400mm.
Build quality is professional-grade with weather sealing and robust construction. The remarkably compact dimensions for a 400mm are the lens's defining characteristic — it packs into bags and travels in ways that conventional super-telephotos cannot. The lightweight design reduces fatigue during extended handheld shooting sessions.
On the used market, the EF 400mm f/4 DO IS remains uniquely appealing for its compact dimensions. While the newer DO II version improved optical quality, the original still provides a 400mm f/4 in a package dramatically smaller than conventional alternatives. For travelling wildlife photographers, the size advantage is genuinely significant.