This is my favorite lens on my DMR and I can t bare to convert it to a Nikon mount. So I am looking for a used 180:2.8 APO to use on my D3X. The later versions of this lens ..the rear element is about 3/4 to 1 inch recessed to allow for the use of the 1.4x extender ...this affects fair market value . Let me know if you would like to sell one of these lenses .