The rings do not have lenses, so there is no fear of deterioration of the optical quality of the set, even when using high-class lenses. They are mounted between the camera and the lens, and their action consists in changing the distance between the lens of the lens and the photographic film or CCD matrix in the camera - which allows a larger scale of reproduction. By using three rings (rings can be used separately or combined in any combination) we are able to take macro photos with very large reproduction scale and very good quality.