The high image quality you would expect from a
flagship lens
The use of 2 fluorite and 1 Super UD lens elements correct chromatic aberration, removing one of the last hindrances to ideal image quality on a super telephoto lens and achieving stunning visual resolution and overall contrast. The EF400mm f/2.8L IS III USM also newly features Canon’s own Air Sphere Coating (ASC) technology, which incorporates air with a lower refractive index than optical glass into the coating, forming an ultra-low refractive layer that suppresses lens flare and ghosting.