Former chief official White House photographer Pete Souza is in Chicago this week to debut his new book Obama: An Intimate Portrait (Little, Brown & Company), which reproduces more than 300 of Souza’s photographs of the most memorable moments of the Obama presidency.

Throughout President Obama’s two terms, Souza captured nearly two million photos in portraits both highly classified and disarmingly candid—everything from unguarded time with the family to encounters with children and interactions with world leaders.

According to Souza, the former president couldn't choose his own favorite (it changed every time he saw a new picture of him with Sasha or Malia). And while Souza won't call a single shot his best, here are a few of his favorites, along with the behind-the-scenes information that brings them to life.