 ILM filmed starships using motion control for timed and computer @-@ assisted model movement . The ship models required multiple camera passes because different parts of the ship and its lights were filmed at different exposure levels . The Excelsior required eight passes to supplement the main " beauty pass " , the Enterprise six . ILM could have combined passes with multiple exposures , but not without risk ; " If anything got out of synch , or somehow we dropped a frame , we would have to reshoot — and then you 're stuck . You 've ruined two pieces , two elements , " Farrar said . 
