is drawn in or out the extension of the spring changes by only a fifth of that distance, so that the tension force of the spring will not change much. The result is that the spring-pulley system can produce a fairly constant tension in the cable over a large range of movement. The almost constant force exerted by an iso-elastic system is employed in the armature of a steadicam, to counteract the constant force of gravity on the camera's and mount's mass. The result is that the weight of the camera is almost exactly balanced by the tension force throughout the entire range of vertical movement, so even when the operator jumps vertically, the camera will retain its vertical position due to inertia, but remain balanced, just with the armature at a different angle. As a result, the camera doesn't bounce up to the 'balanced' position after a move, for example when the operator steps up onto a curb from the road. This allows the camera to be more isolated and independent of the operator's moves. The operator can of course deliberately move the camera up or down, if desired. In reality however camera operators find it preferable for the arm to not be perfectly iso-elastic so that the camera will naturally rise to a comfortable operating height; the springs will be tensioned so this only happens very slowly and without bouncing so as to maintain the smoothness of the camera's motion." See also Precision engineering References Engineering concepts Cinematography