Black Lens structure (elements/groups): 18/12 Closest focusing distance: 1.4 m Auto focus With its multi-layer diffractive optical (DO) element, Image Stabilization (IS) and Ultra-Sonic Motor (USM) technologies, the EF 70-300mm f/4.5-5.6 DO IS USM is a celebration of precision optics. The lens sets new standards in compact size and high image quality. IS technology allows razor sharp images at lower shutter speeds, while rear focusing USM delivers fast, silent auto focus.The DO factorThe EF 70-300mm f/4.5-5.6 DO IS USM is the world's only zoom lens to incorporate a DO element. Introduction of a new triple-layered DO element not only makes the lens more nimble, it delivers unrivalled imaging performance. The DO element is combined with normal refraction elements to compensate for colour aberration. This achieves levels of colour aberration correction that could previously only be achieved with the use of fluorite elements or Ultra-low Dispersion (UD) lenses. The result: superb image qua