Mount the camera to the bracket and put it on the tripod. You will need to find the correct nodal point for your particular camera and lense combination. That is the reason the bracket has a long slot. So you can take a series of pictures while sliding the bracket back and forth until you find the perfect nodal point. Once you find the perfect nodal point for your camera, mark the bracket so you know where to drill the hole on your real bracket. You can also use this bracket to find the nodal point for the wide angle and the fisheye lens.