FYI Metabones Speed Booster for Nikon G
metabones released the nikon G speed booster in her website
"Metabones has introduced Nikon G-type versions of its Speed Booster lens adapter for Micro Four Thirds and Sony NEX cameras, which include a control ring for aperture setting with lenses that don't have aperture rings of their own. The Speed Booster itself is a lens adapter that that reduces the focal length by a factor of 0.71x, and increases the maximum aperture by 1 stop, effectively allowing lenses to give very similar angle of view and depth of field control on APS-C mirrorless cameras as they do on full frame. The Nikon G-type adapters are available to buy now for $429 from Metabones' website."