Absolute spectral intensity calibration of optical detectors has always been difficult. Up to now it was only possible through the use of expensive sources, which are cross-calibrated against national standards. At the 28AM optical meeting, a simple theoretical approach to absolute optical calibrations was described using any ordinary tungsten light bulb . A key element of the theory is transforming tungsten into its equivalent blackbody radiator. This permits direct application of Stefan-Bolzmann’s and Planck’s formulas of radiation. The theory has been tested by comparing three household tungsten light bulbs with a calibrated source at several wavelengths typically used in auroral research. The results of this experiment are most encouraging.