On both pics Sigma 50-500 was set at 500mm -max focal length. Pic on the left side shot at f22 with no TC, and the pic on the right side shot with Sigma 2x teleconverter added. In order to get the same object size, camera with the tripod moved from 3.5 to 7 meter distance. That's why some perspective and background color has changed. Some blur on the righ hand side pic could be due to wind gusts, but in general, Sigma 50-500 with 2x TC and set to maximum focal length (total equivalent focal length is 1500 mm !) doesn't give picture quality you've dreamed about!