The Nikon BR-2 is a metal reversing ring that allows a compatible lens to be mounted backwards on a Nikon camera or bellows attachment. This technique enables high magnification, making it particularly useful for macro photography and capturing small subjects.
The ring is designed for lenses with a 52mm filter thread. For direct mounting on the camera, a focal length between 20 and 60mm is recommended. Lenses with a larger filter thread may require an additional adapter.