I own a Tokina 11-16mm and use it with the 5N. I purchased a VELLO brand (LA-NEX-NG) Sony NEX to Nikon G Lens adaptar from B&H. I think it may have been about $60. It works well with the lens, has a ring to control the aperture on the Tokina, a tripod mount that you can remove with a slim screwdriver, and is a perfect fit for both the camera and the lens. You could probably find a cheaper adapter, but I was willing to pay a few dollars more knowing the adapter would fit properly and without problems.