City Light Suppression Broadband Filter SVBONY city light suppression broadband filter is designed to improve the visibility of various deep sky objects, by selectively reducing the transmission of wavelengths of light pollutants. specifically those produced, by artificial lighting including mercury vapor lamps; both high and low pressure sodium, vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere, such as sky glow. Extinction Treatment: aerometal material precise CNC machining sand blasting process black anodized finish extinction treatment to prevent reflection laser. Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and optical density of off-band. Ultra-thin filter cell minimize vignetting by possible. 90% transmission of main nebula emission lines (i.e. Ha 656nm, OIII 496nm&500nm, SII672nm and H-beta 486nm). 0.1% transmission of off-band, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nmand 578nm). Compatible with color CCD cameras and unmodified DSLRs. CLS filter: engraving no fading CLS with wider pass-band than UHC and hence is more favored when observing under mild to moderate light pollution. Light pollution filter do not eliminate the effects of light pollution or increase the object's brightness; in many cases, they increase the contrast between nebula and night sky, not brightening the nebula. Warning: the filters of SVBONY are not designed for sun observation, don not look directly into the sun with SVBONY filter, otherwise it will burn the eyes. UHC Telescope Filter Improves Image Contrast of Nebula and Deep Sky Objects The SVBONY filter is a better choice for all digital imaging with digital cameras; DSLR camera; CCD cameras; modified Webcams and telescopes.