Pete Souza is the current Chief Official White House Photographer under Barack Obama and the director of the White House Photography Office. If you follow him on Instagram you can see many "behind the scenes" photographs he posts with his access to the President.
Pete is a fabulous photographer and as you can see is very prolific in sharing his work with the public.
His recently published Medium article Behind the Lens: My Year on Instagram 2015 talks about his last year of images as well as much of the equipment that he uses.
Souza is a former photojournalist who has freelanced for National Geographic and Life magazines. He covered Obama's arrival to the Senate in 2005 and continued to document his rise to the presidency in 2008. He's noted as producing the first digital Official Presidential Portrait.
Souza and his staff are extremely prolific producing around 20,000 images a week.