Balancing the refined optics, this 24-70mm f/2.8 also sports a ring-type USM and internal focusing mechanism to enable quick, quiet, and accurate autofocus performance, as well as full-time manual focus override. Additionally, this lens is weather-sealed and has a protective fluorine coating on the exposed elements for use in trying environmental conditions.

• Standard zoom is designed for full-frame Canon EF-mount DSLRs, however can also be used with APS-C models where it provides a 38.4-112mm equivalent focal length range.
• Bright constant f/2.8 maximum aperture affords consistent illumination throughout the zoom range and also affords greater control over depth of field for working with selective focus techniques.
• One Super Ultra-Low Dispersion element and two ultra-low dispersion glass elements noticeably reduce color fringing and chromatic aberrations for high clarity and color fidelity.
• Three aspherical elements minimize spherical aberrations and distortions for improved sharpness and accurate rendering.
• Super Spectra coating has been applied to individual elements to minimize ghosting and flare for greater contrast and color neutrality when working in strong lighting conditions.
• A ring-type Ultrasonic Motor (USM), along with an internal focusing design, optimized focusing algorithms, and a high-speed CPU, is employed to deliver fast, precise, and quiet autofocus performance as well as full-time manual focus override.
• Rounded nine-blade diaphragm contributes to a pleasing out of focus quality that benefits the use of shallow depth of field and selective focus techniques.
• Protective fluorine coating has been applied to the front and rear element to resist fingerprints and smudges and to make cleaning these elements significantly easier.
• As a member of the esteemed L-series, this lens is sealed against dust and moisture for working in inclement environmental conditions.
• Zoom lock lever secures the zoom position at the wide end to maintain a compact form factor and protect the lens when not in use.