CONTINUOUSLY VARIABLE, REMOTE COLOR TEMPERATURE ADJUSTMENTS FOR METAL-HALIDE LAMPS IN CINEMATOGRAPHIC APPLICATIONS

One approach to achieving rapid and easy manipulation of color temperature has been investigated, the Liquid Dynamic Color Filter (LDCF). A thin layer of liquid - a pure iodine and ethyl alcohol solution - is continuously circulated, allowing the concentration of the solution to be changed and introduced to the filter layer. A spectrometer and color temperature meter are used to investigate the effect of the solution's concentration on a typical HMI lamp's color temperature. It was found that the color temperature of the filtered HMI lamp was a well-behaved, smooth function of the concentration. Color temperatures in the 5600-degrees K to 3000-degrees K range have been obtained. Spectrometer tests show that the iodine and ethyl alcohol solution does not introduce spectral discontinuities. However, the solution has shortcomings as an LDCF filtering solution. This is evident when the color correction and light balance ratios are investigated. Future work on improvements to the filter solution is planned.