Very few binoculars with 64° Afov eyepieces have a sharp outer fov. See how your binocular compares with a dozen others
http://www.cloudynights.com/item.php?item_id=1761

Unfortunately the Nikon Action is one of the worst in this respect. the Nikon Action Extrreme is no better than the Action. But, compare both of those to a Pentax. Even with a much narrower field of view, it shows a wider shaper Tfov.

edz