Previous iterations of this lens lacked certain features to compete directly with the premium offerings from the rival marques. But, to their credit Sigma has addressed each shortcoming with the relevant upgrade. While this has increased the price each time, the current $3,600 ticket is still well under what you would currently pay for either the Canon or Nikon 300mm f/2.8 models. Not only that, but it may even save buying a 70-200mm f/2.8 in certain cases. Given the potential savings and the excellent optical performance, the Sigma must be worth a closer look.