OPTICAL SYSTEM AND ASTRONOMICAL ARTIFICIAL-LIGHT REDUCING FILTER MAINTAINING COLOR

摘要

PURPOSE:To take an astronomical color picture of good quality by using a thin- film colored filter having prescribed spectral transmissivity. CONSTITUTION:A colored filter of a thin gelatin or acetate film is used which has the center at 500nm and permits =620nm light to pass through while occluding =440nm and 530-620nm lights of the Hg bright line. This filter permits the blue, green and red lights of a color film to pass through equivalently. Thus, an astronomical color picture of good quality can be taken.