Tullis met Austrian climber Kurt Diemberger in 1976, and by 1980 they were working together on lecture tours. In 1981, Diemberger hired Tullis as a technician for an expedition to Nanga Parbat, and their high-altitude filming career began. It would include, in the following years, expeditions to the North ridge of K2 and the unclimbed North-East ridge of Mount Everest. In 1984, Tullis and Diemberger climbed Broad Peak, and after more film work they went on an expedition to climb K2, in 1986.