The Dawn Wall, a new film from documentary filmmaker Josh Lowell, follows rock climbers Tommy Caldwell and Kevin Jorgeson as they attempt to become the first people to free climb “The Dawn Wall,” an extremely difficult section of El Capitan, the 3,000-foot rock in Yosemite National Park. At the premiere of the film, we spoke with Lowell about the logistical nightmares of making a movie on the side of a giant rock.