From an interview with the FX director for Superman 4 from Superman Cinema-http://www.deceptions.net/superman/superman4/s4_production/special_effects/ellenshaw_interview2/page1.htm Q3. Did you consider using yellow screen sodium vapour traveling matte work [from your Disney roots] to remove the problem of matting superman's blue tights? A. Absolutely it was considered. Two big limitations prevented us: Reason #1: The widest lens available for the sodium camera is a 40mm, which is pretty long actually. This is because wider focal length lenses don't fit. They hit the prism that is placed right behind the lens mount. Reason #2: There were no anamorphic lenses for the sodium camera, so it meant we would have to shoot Super35, which yields a pathetically small negative area for 2.40:1 [the aspect ratio for all the SUPERMAN movies]. Especially considering you have to dupe the shots because they are opticals.