I looked at a D800 today and noticed that when you go into one of the crop modes, a frame appears in the VF showing you the area that will be in the image. Outside the frame, the image still appears but is slightly blurred.
For whatever reason, I actually thought the image in the VF would enlarge when you used a crop mode, in effect, filling the entire VF with the portion within the newly sized frame (my mistake). But now I am not clear on any benefits to be attained through using the crop mode in camera, except perhaps to save a little time in post, with the disadvantage that you no longer have an image from which you could make arbitrary crops after the fact. It's a done deal.
As it turns out, I will be giving up my D7000, my only DX camera, and "replacing" it with a D800 (committed to that at this point - my wife wants and will get the D7000 ) and it seems that I will not be able to focus long shots as easily as I could on the D7000 without the benefit of a true "enlargement" of the image in the sensor. I had been using my D7000 primarily for long shots via an 80-400 and 300 f/4 with 1.4 TC.
Does anyone now using a D800 have any comments on this? Dennis