Overall the Sigma 120-300mm 2.8 has been one of the most impressive lenses I have used. Not only did it offer unbeatable sharpness for any lens, Sigma managed to pull it off on a zoom lens at f2.8. In addition, there really is nothing in the way of competition from Canon and Nikon in this category and 300mm f2.8 lenses without any zoom range cost twice as much. Throw on a teleconverter and the Sigma becomes a 480mm f4 lens easily blowing away the $6500 Canon 400mm f4 lens. With a focus motor that easily keeps up with the action, and 2 custom focus modes programmed through the Lens dock, the Sigma 300mm is definitely the lens to beat in this category. While it did make a great lens for portraits and wildlife, the real home for the Sigma is likely for sports that often shoot in the 120-300mm range and need the zoom capabilities for when the action moves around. It may be larger and heavier than most of your other lenses, but it delivers where it counts and offers the quality to easily justify the $3600 price tag.
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