Speaking as one who doesn't know a whole lot about tri-pods, i use a Benro A-300EX, on their site they recommend using something around a 70-200 f/2.8 lens or smaller with it. I have used a Canon 300mm f/2.8 IS with it and had no problems. I personally like this tri-pod and have had no problems, I realize this wont work for a 500mm f/4 but maybe it will speak to the quality of the brand some. In the end read reviews. then make your decision, hope i helped some []