Hi, I'm new to all this and the Nikon D5100 is my first DSLR. I'm going on a cruise with my family and three kids, and would like to capture nice memories both onboard and outside during the excursions. I don't want to carry too many lenses with me, so I'm wondering which lens would be the best? My kids do not like to stand and pose for me, so I usually shoot candid photos. Any advice would be greatly appreciated.