A close up lens developed exclusively for the sigma 18 300mm f35 63 dc macro os hsm contemporary lens which will not affect the optical performance of the original lens it offers a maximum magnification ratio 12 and changeable angles of view enables zoom macro photography the minimum focusing distance of the lens is 39cm its maximum magnification ratio is 13 and the working distance is 14cm which is similar to macro lenses in addition to this a close up lens aml 72 01 optional ac