If you own a Nikon D750, by now you've probably read about the confirmed reports that many D750 owners have a problem with lens flare in images, under specific conditions, due to the D750 itself. At certain angles, an ugly dark band shows up across the top of images, separating lens flare from the edge of the frame.
On December 29, 2014 Nikon acknowledged the problem and stated they were working on it. Then on January 9th, Nikon announced they planned to offer free D750 inspection and servicing, including all shipping costs, of the D750's light-shielding components and would adjust, as necessary, the AF sensor position which apparently is the major cause of the dark banding problem.