In my 4 Disney Cruises, I have noticed that when you board the ship, you have choices. The first thing you come to is the photographers. If you do not want your picture taken, wait till the photographers are preocupied with some other family and just walk right through. Next is the CM's just inside the door calling out your name, again, if you don't want to be bothered, just walk right through. If you don't want all the fuss, don't make eye contact and walk like you have a purpose. I am not saying to be rude, but we have slipped by them our last 3 Cruises. They ask your name before you announce it and they are most of the time being asked questions by guests and other CM's.
It is loud enough for the camcorder to pick it up as they have microphones and pipe it through speakers.
We generally do not like having our picture taken when we board as we have been traveling all day, are hungry, tired, and each have a few carry on items. We wait for the other photo op's.