The focusing capability of the attachment lenses is expressed in diopters: +1, +2, +3 ... The higher the value, the greater the focusing ability. What reproduction scale can be obtained with the lens? The greater, the greater its focusing ability and the greater the focal length of the lens used. At 100 mm focal length and +4 diopter lens we get a scale of 1: 2.5 - this is enough for photographing flowers or butterflies. The object distance is about 25cm. The use of a 200mm lens in combination with this lens gives a scale of 1: 1.25, with practically the same object distance.