I just got a D810 and I have never used a AF-ON button before. I am not sure what it does.
I started in the days of manual everything cameras and my habit is to see a subject ( I do street photography) place the central focusing
area on that subject, press the release 1/2 way to freeze the focus and exposure for that subject, re-compose and then hit the shutter
release.
How would I incorporate the AF-ON button into that workflow? I seem to be hearing that a camera as sophisticated as the D810 can allow
you to set focus on a subject, recompose and then follow that subject if it happens to move.... WOW. How would one set that up with the
D810?
Thanks