"Ask the photographer how his camera stores photos, most cameras these days do not have a built in memory and rely on a SD card to store pictures, if that's the case, offer to buy the SD card and get it back when the session has finished, that way only you have copies of the photos.
You are totally wrong! Any digital camera has its own built in storage as well as the ability to store images etc to a removable SD card!
That's not correct either, all cameras do have internal storage but in most DSLR cameras it is nothing more than a buffer that holds the image before moving over to the card, it holds very few pictures and can not be accessed to retrieve photos, my fuji which is not DSLR is the same, no card no photo.
Google it, you will find no end of people moaning about the lack of memory in most brands of cameras."