Anywhere, anytime, everywhere on the ship and on the pier. We even had videographers on our excursions. Be prepared to make some difficult choices, because most of them are really good.
I second joergr's comments;
I use to get a little annoyed by all the photo taking; but have come to accept it as part of cruising. And as joergr says, some are really good.
kjh, you will be bombarded with photo ops. What our family usually does is wait until the night before disembarking and pick out our favs. Photos can get rather expensive. They will leave the photos out all week for you to choose from. If you are absolutely positive you don't want a photo, throw it into the recycle container they have in the photo section.