Star Wars: Episode V - The Empire Strikes Back: Behind-the-Scenes

Phil Tippett and Jon Berg stop-motion animate a shot with all three walkers (the background walkers are cutouts). Originally the plan had been to photograph the walkers against four-by-five Ektachrome transparencies shot in Norway; when these didn’t work as planned, matte artist Mike Pangrazio copied select Ektachromes onto large scenic backings.