This moose and two other bulls were too busy eating to be bothered by us - on the other side of the Gros Ventre River at Grand Teton National Park. We watched and photographed them for more than half a hour while they moved around and ate.
Canon 40D, 500 f4L IS at f/5.6 and 1/640, ISO 800, no flash, from a tripod - about noon on 9/1/08
Good head turn and eye contact. I agree that the missing legs are distracting. Seeing you were using the 500mm lens, if you did not have a shorter focal length, going for a vertical of the head and shoulders would have been a good option.