The Canon EF 300mm f/2.8 L IS USM is a professional grade large aperture telephoto lens designed to offer the best possible image quality while shooting in demanding situations.
Optical design and construction are first rate as is to be expected from a Canon L-Series lens especially one near the higher end of the line. Image quality is excellent thanks in part to some well placed UD and Flourite elements. The f/2.8 maximum aperture allows easier use of faster shutter speeds for action photography as well as enabling brighter viewing and autofocus acquisition in low lighting. Maximum aperture yields considerable background blur and seperation for portraits with a serious sense of depth and the bokeh is beautiful too.
Canon’s previous EF 300mm f/2.8 has been a very popular lens and was considered by many to be the gold standard for a 300mm. Never complacent, Canon has made this sequel a real technological marvel of a follow-up by adding Image Stabilization while further improving autofocus speed, construction, and environmental sealing.