Characterized by its versatile zoom design, image stabilization, and relatively lightweight and compact design, the EF 70-200mm f/4L IS USM is a Canon L-series lens spanning a useful portrait-length to medium telephoto range. The constant f/4 maximum aperture allows you to maintain a consistent exposure throughout the zoom range and also contributes to the sleeker form factor when compared to other 70-200mm lenses. In regard to its optical performance, this lens employs one fluorite element and two ultra-low dispersion elements, which work in concert to suppress chromatic aberrations and color fringing for notable clarity and color accuracy. A Super Spectra coating has also been applied to control flare and ghosting for improved contrast when working in harsh lighting. Complementing the imaging capabilities, this 70-200mm f/4 also features a four-stop-effective Image Stabilizer system that minimizes the appearance of camera shake for sharper handheld shooting. A ring-type USM and internal focusing mechanism also afford quick, quiet, and accurate autofocus performance, as well as full-time manual focus override. Additionally, this lens is weather-sealed for use in trying environmental conditions.