Yes it is natural for most people to clam up in front of the camera, it is the photographers job to make them feel comfortable and bring them out of their shell, that is what separates an armature from a professional. Lets face it every hot girl with a camera thinks that they are a photographer these days!

Very interesting. I wish that our professor would have shared this when I was studying fine art photography at the University of Florida. Even having studied fine art photography and majoring in photojournalism I learned more about the history of photography in five minutes than in the last four years of college.