LRPF (Light Pollution Reduction Filter) is a light pollution filter that cuts off the effects of city lights, sodium lamps, mercury lights, and reduces color clubs. Mainly efficiently cuts light from 570nm to 600nm, making it a perfect item for night scenes and starry skies. This product is a round frame type and has been made to meet the requests of astronomical photographer Takao Nakanishi. Made with high quality SCHOTT (Shot) B270 glass. The visible light transmittance is very high, and the ultra-precision polishing ensures high flatness accuracy on both sides.