Sophisticated Optical Design Six "F" Low Dispersion (FLD), two Special Low Dispersion (SLD) elements, and five aspherical elements markedly reduce chromatic aberrations and color fringing throughout the zoom range for improved clarity and color accuracy. Also, increased control over sagittal coma flare yields high resolution across the entire frame. In addition to superior optical performance, the five aspherical elements contribute to the lens' compact build with their thin, highly polarized construction. The bright, f/2.8 aperture and rounded 11-blade diaphragm produce a large, beautiful bokeh effect. Super multilayer and nano porous coatings have been applied to lens elements in order to minimize lens flare and ghosting and contribute to producing contrast-rich and color-neutral imagery, even in backlit conditions. The lens was also designed to suppress focus breathing as the angle of view changes across the zoom range, creating natural-looking focus pulls when recording video. Focus Faster, Focus Closer The introduction of a linear motor high-response linear actuator (HLA) to drive the autofocus yields focusing speeds more than three times faster than its predecessor. At the wide-angle end of the zoom range, the minimum focusing distance improves to 6.7" with a maximum magnification of 1:2.7 to suit working with close-up subjects or in tight spaces. Built Strong and Svelte Maintaining the same number of lens elements, the overall length has been shortened to 4.8" while the weight has been reduced to 1.6 lb. The aperture ring features both click and lock switches for improved handling during use. The robust internal structure features metal parts for the zoom extension, while the exterior boasts rubber seals in the mount to protect the lens from dust and moisture. Two integrated AF-L buttons can be programmed to adjust various shooting settings and the lens also features a dedicated AF/MF switch and a zoom lock switch to prevent the barrel from accidentally extended.