Kristen Stewart felt exposed while shooting Ang Lee's 'Billy Lynn's Long Halftime Walk'.

The actress co-stars in the movie with Garrett Hedlund and Vin Diesel and admitted that the director's decision to film in 4K resolution, native 3D and at the rate of 120 frames per second, and says every take was ''raw and real'' because there was no room for error.

Speaking to The Hollywood Reporter, she said: ''When you're shooting in the way that we always do, there are certain things that people don't see. I'll finish a take on any other movie and I'll want to do it again, they'll tell me, 'No, it was great,' and I'll say, 'No, trust me, I was lying'. On this, there's no room for that. You see everything. It had to be raw and real. I thought it was awesome, it was so cool - I was like, 'Push me harder!'''

Garrett also revealed that Ang warned his cast against overacting.

He explained: ''[Lee] told us all at the beginning, 'If you try to act, you're gonna look like you're acting, because the resolution is so high. You can't act; you just have to be.' He just wanted everybody to be natural.''

And Vin was hugely impressed with the director, adding: ''Seeing the movie is such a heavy experience. The nuances in the movie, the proposed message in the movie, is kind of heavy. After you saw the credits, everyone was like a deer in headlights. ... [It] takes you a place you don't expect to go in a war picture, and to have a war picture simplified in a statement of love is a testament to what Ang has done.''

The movie is based on the novel of the same name, which follows the story of 19-year-old private Billy Lynn, who returns to the United States from Iraq as one of a group of war heroes, following a particularly intense battle.

The heroic men are then sent on a 'victory tour' by the United States government but soon find out their heroic ending isn't all what it seemed as they are told they will have to return to war.