The EF 24-70mm f/4L IS USM Lens from Canon is optimized
for full-frame 35mm sensors, and another entry into Canon's high
quality L-series of lenses. It has two Super Ultra-low Dispersion (Super
UD) and two standard UD lens elements working together to minimize
chromatic aberrations, and reduce color blurring around the edges of
your subject. Its two types of aspherical elements combine to help
reduce spherical aberration over the entire image area and the full zoom
range. Optimized lens coatings help ensure exceptional color rendering
while minimizing ghosting.
Its ring-type Ultra Sonic Motor (USM) and high-speed CPU, with optimized
AF algorithms, ensure you experience quick, quiet and precise
autofocusing whenever you need it. The lens has improved dust and water
resistance to protect it from damage outdoors, while fluorine coatings
on the front and rear lens surfaces resist fingerprints and smearing.
The circular nine-bladed diaphragm delivers beautiful, soft background
effects. A zoom lock lever holds the zoom position at the 24mm wide end
for safe transporting while attached to an EOS DSLR camera over the
shoulder - preventing lens creep.