Found out something new about D7i....
This probably already known but it was new to me & I have had the camera for some time !
When in full manual mode & judging the accuracy of the selected exposure if you watch the EVF as you press the shutter halfway you will see the screen momentarily darken or lighten before it settles down. The closer you are to the cameras preferred exposure the smaller will be the perceived difference.
If you want to play safe you can then adjust speed to bring it a little closer to the cameras choice or perhaps take two shots & judge later.