Color separating optical system for a television camera

In a color separating optical system for a television camera comprising a color separating optical system composed of a plurality of prisms provided between an objective and one or more television image pick-up tubes, the improvement wherein means is provided for inserting between said prism and said objective any one of a plurality of glass elements having parallel flat sides and of different thicknesses, wherein the thickness of each said glass element is determined in relation to a particular type of image pick-up tube, whereby insertion of a glass element adjusts the glass length of the optical system to the requirements of a particular type of pick-up tube.