Ie. 280mm. No more and no less.
Please note, the following photo has no artistic interest. It is only used to evaluate the field-of-view of a FF camera compared to a Nikon 1 (2.7 crop factor).
Same point of view, only a little higher (the cedar tree branches have a different position)
Different camera + lens setup: Nikon D600 (FF) + TC20eIII + Nikkor 200-500 @ 378mm (or in the vicinity, as visually accurate as possible).
The infamous EXIF field -ExifIFD:FocalLengthIn35mmFormat yields 750 mm, only 6mm difference from the above nighttime picture
You can see that the horizontal field of view for a FF camera @750 mm corresponds fo the horizontal FOV for a Nikon 1 @ 280mm, accounting for the 2.7x crop factor.
N.B. I'm not talking DOF, I'm talking FOV.
You could have the same exact vertical framing if I had taken the time (no, I didn't have the time!) to position the second camera EXACTLY as the first, that is a little lower down.
Good enough for me.
Ciao from Massimo