"Using this lens for wildlife photography to capture bald eagles on a nest that is 300 to 400 yards away. Use a Nikon D3x and Nikon 1.4 teleconverter and photos are crisp and clear. Lens is supported with a Wimberley WH101 Head w/quick release and Giottos Aluminum 3-sec Tripod. Teleconverter produces a 860mm lens. Auto focus is quick and acurate." bhphotovideo.com