Fun Fact: The Hunger Games 3 will be the first film in the series to be shot digitally.
Why? According to director, Francis Lawrence (who is also responsible for another great classic -"Constantine") the film is dark. Not only its genre, but the footage is actually dark enough that the feature deserved a full on digital take regarding lighting.
Since Mockingjay Part 1 takes place mostly underground with low lighting, the digital format helps the process, leaving a sharper look and better imaging for post. According to a previous article from Wired, "One of the cooler visual tricks in Catching Fire — for those who see it in IMAX – happens when Katniss first enters the arena. As she ascends into the 75th annual Hunger Games in her tube, the actual screen extends vertically into its full IMAX glory. Expect none of that in The Hunger Games 3 Mockingjay."
“We went from film to digital – mostly because it’s a very different kind of story and most of it takes place underground and in District 13.” - Francis Lawrence