70-300mm f/4.5-5.6 DO IS USM
... diffractive optical (DO) element, Image Stabilization (IS) and Ultra-Sonic Motor (USM) technologies, the EF 70
f/4.5-5.6 DO IS USM is a celebration of precision optics. The ... speeds, while rear focusing USM delivers fast, silent auto focus.
The DO factor
The EF 70
f/4.5-5.6 DO IS USM is the world's only zoom lens ...