Schott substrate material
Glass thickness 2.0 mm (1.25”/2”/36mm) and 1.0 mm (Clip series)
Surface Quality: 60/40 (Refer to MIL-O-13830)
Fine-optically polished to ensure accurate 1/4 wavefront and < 30 seconds parallelism over both surfaces
95% transmission of main nebula emission lines (i.e. Ha 656nm, OIII 496nm & 500nm, SII 672nm and H-beta 486nm).
0.1% transmission of off-band, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm). Transmission of 0.1% is equivalent to OD3 (Optical Density), and a high optical density value indicates very low transmission, and low optical density indicates high transmission.
- Details
- Category: Filters
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By Sismo Astroberry
Optolong 2" City Light Suppression
The Optolong CLS (City Light Suppression) broadband filter is designed to improve the visibility of various deepsky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightings including mercury vapor lamps, both high & low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Together with the high transmittance in main emission lines of nebulae, namely O-III(496nm and 500nm), H-beta (486nm), N-II(654nm and 658nm), H-alpha(656nm) and S-II(672nm), the filter is suitable for enhancing the contrast and details for both visual and photograghic purpose at sub-rural area.
