When I teach a DM is my extra eyes and hands to lend assistance to students when they need it. When I am on vacation, I expect a thorough briefing and don't touch my gear. That earns you your tip. I explain to the DM that I am taking pictures just let me do my thing, promise will not stay in longer than an hour,usually find cool critters close to the boat. In Hawaii this Feb. the DM always ended the briefing by looking at me and my buddy Jason and would say "yeah, I know, see you at the end of the dive."