Sigma 17-50 mm F2.8 EX DC OS HSM Lens (77mm filter thread) for Canon lens mount (Electronics)
After I have done my very difficult when choosing a fast standard zoom for my EOS 7D I would like to briefly describe my motives for purchasing the Sigma 17-50, F2.8. Background: EOS 7D with EF24-105 L F4, F4 EF70-200 L, EF-S 10-22, EF 50 F1.4 Criter