Tristimulus colormeters for color measurement on light sources, e.g. lamps, luminaires, light signals, flares, monitors, displays, glasses and filters. Colorimeters of highest precision for absolute measurements with the tristimulus method acc. to DIN 5033 part 6 resp. CIE Publ. No. 15.2 (1966). Colorimeter heads with Si-photoelements and high precise spectral adjustment to the CIE color matching functions