After taking pictures for an hour, my D7100 suddenly got a darkened viewfinder and crazy focus issues. It would seem something went bad ... Back home I charged and changed batteries to no avail, and tried all manual settings with manual focus. I can take pictures, but the focus issues persist in AF setting. If I open the lens all the way to 1.8 the viewfinder is nice and bright, but locked on f22 it is dim. Live view is also dim. I will call Nikon on Monday, but I wonder what others here have experienced with these problems. Thanks!