Sigma 500mm f/4 DG OS HSM Sports Lens for Canon EF 185954 B&H
Sigma APO 200-500mm f/2.8 (400-1000mm f/5.6 w/ Included 2x Teleconverter EX DG | eBay
Used Sigma APO 200-500mm f/2.8 (400-1000mm f/5.6 with Included 2x Teleconverter) EX DG Autofocus Zoom Lens for the Nikon AF-D Digital Camera 597306
Amazon.com : 500mm (w/ 2X- 1000mm) f/8-32 HD Preset Telephoto Lens for Canon EOS 80D, 77D, 70D, 7D, 6D, 6D Mark II, 5D Mark IV, 7D Mark II, T7i, T7, T6i, T6,