Nano USM focus motor
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Nano USM focus motor

A Nano USM focus motor handles AF, and the 24-70mm F2.8 has only one focus element, which results in fast autofocus at all focus distances. We've been impressed with the speed of Canon's Nano USM technology in previous lenses, and welcome the inclusion of the technology in the latest RF lenses. It's a feat we don't imagine was particularly easy, given that traditionally Nano USM motors could only move small, lightweight elements.

We're also told that the position of this element - near the rear of the lens, close to the sensor - is the main contributing factor to the elimination of focus breathing.