With the back component of the adapter users can add a 72mm filter to improve picture quality at the widest zoom and it will not cause vignetting. In this case lens full zoom function is not applicable.Screw both parts together and add a 72mm filter for macro/close up shotting, however, it may cause vignetting. The lens adapter will protect your camera lens when the lens is extended.  The adapter also allows user to add other lens accessories(as tele/close-up/wide-angle lenses) to the camera. The special design of a smooth inner ring of the lens adapter helps protect your expensive camera from scratching during installation.