The EF70-300mm f/4.5-5.6 DO IS USM telephoto zoom lens is the second model in Canon's EF lens lineup to incorporate a DO (Diffractive Optical element) lens. Equipped with a three-layer DO lens specially designed for use in zoom-lens optics, the new lens possesses an exceeding ability to correct chromatic and spherical aberrations and render high-quality images. The lens element also achieves major reductions in size, realizing savings of 28% in overall length compared to comparable lenses incorporating conventional refractive optical elements. Moreover, the size and weight advantage comes at no cost to image quality, with the EF70-300mm f/4.5-5.6 DO IS USM delivering image quality on par with Canon's L-series lenses. High performance features include image stabilization equivalent to shooting at approximately three shutter speeds faster, a circular diaphragm for improved background blur, and a zoom-ring locking mechanism that locks the lens in the fully retracted position to prevent unintended extension and damage when hanging from the user's neck.