>>On the D7000, AF-on does not start VR but ... > >Based on what I've read, the D7000 starts VR by pressing the >shutter release button, regardless of whether you've mapped >AF-ON to the back button. Correct?
Correct. VR is turned on only by the shutter button.
>If so, is there any practical downside to this? For example, >is there a chance that since focus has already been acquired >via the back button, that somehow VR won't acquire in time for >the faster response? Or does VR acquisition complete no >matter what, potentially negating any faster response? What >about the VR stabilized display in the viewfinder as well?
Regardless of which button is doing the focus, VR takes up to 1/2 second to stabilize. You will see this in the viewfinder as the image jumps around. This is why sports shooters always have VR turned off; they cannot have this 1/2 second lag. Plus, at the shutter speeds they are shooting at, VR is not needed.
---------+---------+---------+---------+ Joseph K Seattle, WA, USA