Batman has always been a dark character, hence his nickname, The Dark Knight. The film sequel pushes that aspect, but director Christopher Nolan was always mindful of its intended audience.
Nolan Directs The Dark Knight
"Part of my creative process is knowing the tone of the film that I'm going to wind up with," said Nolan. "So always knowing that this was going to be a PG-13 movie and that we want kids and families to go see this, you think along those lines and you don't really tend to come up with stuff that's completely beyond the pail. If you assess the film carefully and analyze it with other films it's not a particularly violent film actually. There is no blood. Very few people get shot and killed, compared with other action films. There's plenty violence in the film, believe me. We tried to shoot it and dress it in a very responsible way so that the intensity of the film comes more from the performances and the idea of what's happening and what might happen."
Intensity is indeed the quality that many early viewers have already taken away from the film. "A lot of the intensity comes from the threat of those things that may happen that then don't. There's definitely an intensity to that and I think the MPAA were very responsible in their assessment of the movie. I made it very clear to them that I'd gone into this knowing that it had to be a PG-13 and everyday on set when we were dealing with violent issues I would be careful to tone things down and say, 'Okay, we're not going to use any blood squibs. We're not going to shoot things that can't possibly be in the film.' So it's a very bloodless film. We're dealing with a hero who won't carry a gun and who won't kill people which is almost unique in terms of an action film. I think it's an interesting challenge and I think that it takes the story more interesting places."
A lot of the intensity also comes from Heath Ledger's portrayal of The Joker. "When I was working on the script and he'd gone off to think about what he was going to do with the character, he would call me from time to time and talk about the things that he was working on. The truth is that when you're outside that process before you get to set, it's all a bit abstract. So he was talking to me about how he'd been studying the way that ventriloquist dummies talk and things like that, I'd be sitting on the other end of the film going, 'Well, that's a bit peculiar.' What I'm really hearing is an actor really invested in trying to come up with something very unique. Then when I saw it all come together, the conversations we'd had kind of made sense. I could see where he was coming from with that with the pitch of the voice. He would talk about having it change pitch dramatically in very sudden ways and things like that. That helps the unpredictability of the character. When we were mixing the sound for the film, normally you're sort of flattening out voices to make them clearer, evening out the volume at which they speak, but with The Joker we felt that you had to let it be a little bit out of control in the way that he performed it."
The Dark Knight also envelops some audiences with an Imax presentation that presents some sequences in the full screen size. This was a new technical challenge for Nolan. "One of the big disadvantages of these big IMAX cameras, particularly in low light photography is that they don't have very sophisticated video hookups. You don't actually get a very clear image on the monitor at all. If anything it was more of a case of watching with my eyes and seeing what was really going on because the actual video feed that you get from the IMAX cameras is very dim and it's very hard to see what's going on."