Abstract: Apparatus for producing a three-dimensional effect from a two dimensional image carrier having a focussed area containing principal subject matter and a defocussed area containing incidental subject matter. The apparatus includes a camera lens system, an optical device mounted within said lens system and a stereoscopic viewer. The optical device comprises a module which includes a pair of colored filter elements of different wavelength passbands, the filter elements being displaced laterally on opposite sides of an axis of said module, the module being arranged to cause an aberration to be formed on at least some of the incidental subject matter in the defocussed area but not affect the principal subject matter in the focussed area.