You may already know this, but I could never figure this out. A10 is an autofocus setting that is described as:
"If Yes is selected, separate focus points can be selected for “wide” (landscape) orientation, for “tall” (portrait) orientation with the camera rotated 90° clockwise, and for “tall” orientation with the camera rotated 90° counterclockwise. Select No to use the same focus point regardless of camera orientation."
Seems plain enough now in retrospect if one just reads it rather than reading INTO it. I guess I must have been aware of the Canon 1D X which trumpets a new feature that automatically moves the AF point for one orientation to the other. E.g. in the Canon implementation, if you are shooting landscape orientation with the AF point at top-left and you rotate the camera into portrait, I believe the camera automatically moves the selected AF point to the top-left in portrait orientation.
The D4 doesn't work that way! Now that I FINALLY understand I have 3 different memorizations I can definitely work with that and did so at a theatre shoot tonight. Duh! For example in theatre for Portrait I will extremely often put the AF point at top left. In Landscape I might be top left, top middle, or top right, or even centre; I tend to move the point a lot in this orientation. So I can definitely make this work now that I get it
I couldn't understand why, when I had this setting to YES, sometimes it would appear to work automatically and sometimes no. All the while not realizing that it was merely returning to wherever I had last manually set it to appear!