The EF 400mm f/4 DO IS USM is the worlds first super telephoto lens incorporating "Multi-Layer Diffractive Optical (DO) Element", for camera lenses, and is considered a major breakthrough. The outstanding feature, being its superb ability to correct chromatic aberrations. By incorporating this optical element in the optical design the EF 400mm f/4 IS USM is much smaller and lighter than a comparable lens having conventional optical elements. The Multi-Layer Diffractive Optical Element developed by Canon is a milestone optical element possessing the characteristics of both fluorite and aspherical elements, which has led to the production of high-performance camera lenses.

Filter diameter (mm)52 Drop-in
Max. diameter x length (mm)128 x 232.7
Weight (g)1,940