Sigma 180mm f/3.5 EX DG IF HSM APO Macro Lens for Nikon SLR Cameras Floating Inner Focusing System Fully compatible with all Nikon Digital SLR cameras including the D40 and D40X It is possible to use 1.4x or 2x Sigma Apo Tele Converters Use of SLD (Special Low Dispersion) glass Inner Focus