D600 Dx mode
You have to set AF Point Illumination to OFF for the DX letterbox to appear. Setting a4 in the menus.
It's an odd thing that it only works in that situation. I would consider it an interface bug but I'm sure there is a technical reason why it can't work when the illumination is turned on.
|Fangorn Forest by cand1d|
|Yosemite Falls with Moonbow by Jonathan Shapiro|
from Best Landscape of the Week 4