The production of "The Secret of NIMH" lasted from January 1980 to early June 1982. The studio set out with the explicit goal in mind of returning feature animation to its "golden era", concentrating on strong characters and story and experimenting with unusual and often more labor-intensive animation techniques. Bluth believed older techniques were being abandoned in favor of lower production costs and the only way that animation could survive was to continue traditional production methods. Among the techniques experimented with on "The Secret of NIMH" were rotoscoping, multiple passes on the camera to achieve transparent shadows, backlit animation (where animated mattes are shot with light shining through color gels to produce glowing areas for artificial light and fire effects) and multiple color palettes for characters to fit in different lighting situations, from daylight, to night, to warm environments, to underwater. Mrs. Brisby had 46 different lighting situations; therefore there were 46 different color palettes, or lists of color, for her. Two modern, computerized versions of the multiplane camera were also manufactured for this production.