"I was simultaneously awed by this amazing woman, who seemed to balance her career and family so easily, and frightened by the reality of what a presidential campaign would mean for [them] should her husband decide to run."

Shell shot more than 400,000 images of the Obamas, as Barack went from being a young legislator sitting on a stool at Kerry's event in Chicago to a leader standing at the desk of the Oval Office as the United States' 44th president in January 2009.

"They did not come from old money, they did not have a long family history in politics," says Shell. "Because of this, they were able to understand, and even relate to, some of the stories everyday Americans shared with them."

Shell has collected her favourite images of the family in a new book, Hope, Never Fear. "I hope sharing the Obamas' journey empowers people of all ages, races and genders to believe in themselves, and to use their voices to take control of their future."