The EF 70-200mm f/4L IS II USM from Canon is an impressively versatile telephoto zoom. Well-suited for a range of subjects, from events to portraiture to sports, this zoom is characterized by its constant f/4 maximum aperture to strike a balance between consistent performance and portability. Its optical design includes a pair of UD elements and one fluorite element to greatly reduce chromatic aberrations and color fringing. Version II of this popular lens also sees the inclusion of a revised Optical Image Stabilizer, which now compensates for five stops of camera shake and offers three distinct stabilization modes to suit different shooting applications.  Constant f/4 maximum aperture affords consistent performance throughout the zoom range and also contributes to the relatively lightweight design and compact form factor. 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. The focus Limiter switch lets you constrain the focusing to two different ranges to suit different applications: 3.3'-infinity or 9.8'-infinity. As a member of the esteemed L-series, this lens is sealed against dust and moisture for working in inclement environmental conditions.