Paul Greengrass' "Captain Phillips" is currently entering its second week at the box office having riveted both critics and filmgoers. Much of the praise the film has received has focused on its exceptional realism. Much of that is courtesy of the film's director of photography, Barry Ackroyd, who spoke to HitFix earlier this week about his work bringing the saga to life.

Ackroyd previously worked with Greengrass on "United 93" and "Green Zone." It's clear they see eye-to-eye on most matters; both have backgrounds in documentaries and both are keen to make their films as realistic as possible and appropriately respectful of their subjects. "Sometimes you have to get a very blunt instruction," Ackroyd says. "But when it's working well, very little discussion is necessary. It's an understanding that you have."

Ackroyd says working with Greengrass is quite the immersive experience as the director is ever focused on placing the viewer in the story. "Paul is going to throw you into this world that is tough: 'How do we film a war zone?' With some directors, you'd have to find some highly technical way with CGI. But with Paul, it comes down to 'let's just do it.'"

There was discussion as to whether "Captain Phillips" should be shot digitally, and in that realm of cinematography's consistent evolution, Ackroyd says he's quite flexible. But in the end, "it's about texture and reality and grain," he says, so they "decided to go with something more reliable."

Old-fashioned problems regarding practicality began to emerge, naturally. "You start to find out the limitations," Ackroyd says. "Once we realized what we had to achieve – fishing boats in high seas chasing a rather large container ship, etc. – then we're going to have to be as flexible as we can. I can't carry the zoom lens on a 35mm format. It had to be 16mm, and that's going to have to capture the story."

Ackroyd and Greengrass are also famous for their use of the hand-held camera. Ackroyd says he likes the change to, again, capture things in a real-time vein. "It becomes a natural process," he says. "You can put it on a little tripod with a slider. I also use long lenses, long zooms. Soon, where the camera goes, your mind goes. During each take, it's organic to know when to run at someone, when you let someone come to you."

This is not to say that much of the film wasn't daunting, and Ackroyd knew there would be challenges as soon as he read the script. "Undoubtedly when you read a script set at night with three navy war ships, a lifeboat and a helicopter and the lifeboat needs to be taken down, you're going out there thinking it can't be done," he says. "But with someone like Paul Greengrass, you'll know he'll be supporting you."

Even with Ackroyd's background in documentaries and filming around the world, each new project poses new challenges, and this title was no exception. "I've been about everywhere and every place," he says. "I actually filmed on an aircraft carrier in the Gulf War. I have lots of familiarity with container ships. The bridge or engine room of a ship wasn't a surprise to me. But taking down a cargo ship at sea was something I hadn't done before."

In the midst of the grandiosity of the ships at the heart of the plot, it became very important not to forget what the film was about: the story of an individual and his crew. Truth in a story, he says, "is not something you can reproduce," which is an interesting takeaway given the criticism the film has come under as of late. But that's not to say it isn't a goal.