Optolong CLS CCD Light Pollution Filter - 2" Mounted for Astrophotography - Enhance Deep Sky Imaging for Telescopes & Cameras

This CLS-CCD Broadband Filter by Optolong will drastically increase contrast, brightening faint outer regions on most emission nebulae, planetary nebulae, and supernova remnants from light polluted areas when photographed with a color imaging camera.

The infrared wavelength of 700-1100nm is cut off on the Optolong CLS-CCD Filter, making it different from the standard CLS filter and rendering the CLS-CCD a photographic filter only. There is no need to use a separate IR-cut filter when imaging with the CLS-CCD, because the IR has already been cut for you!

The Optolong CLS-CCD filter works by selectively reducing the transmission of light pollution wavelengths, especially artificial light pollution caused by high and low-pressure sodium vapor and mercury vapor lights. Using a CLS-CCD filter will also increase contrast by reducing the skyglow caused by naturally occurring neutral oxygen emissions in our atmosphere.

The Optolong 2” CLS-CCD Filter is made Schott glass that has been multi-coated with ion-assisted deposition technology to ensure scratch resistance and stability on the central wavelength or CWL. The 2" filter cell is made of lightweight, strong metal and is CNC machined, sand-blasted, black anodized, and then laser engraved. The result is a super thin filter cell that will produce a clear aperture of 45mm.

Transmission Characteristics of CLS-CCD Filter

• 95% transmission H-Alpha 656nm

• 95% transmission OIII 496nm and 500nm

• 95% transmission SII 672nm

• 95% transmission H-Beta 486nm

• High transmission NII 654nm and 658nm

• 0.1% transmission Hg at 435nm and 578nm

• 0.1% transmission Na at 589nm

• Blocks transmission IR 700-1100nm

Quality Filter Materials:

• Schott B260 substrate material from Germany, 2.0mm thick

• CNC machined and black anodized aero-metal filter cell that is ultra-thin to provide largest clear aperture; Laser-engraved to prevent fading

• Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with Ion-assisted deposition

Optolong Filter Manufacturing Processes and Parameters

• Filter substrate is fine-optically polished to 1/4 wave and <30 parallelism over both surfaces

• Surface quality, according to MIL-O-13830, is 60/40

• Main nebula emission lines have a transmission of 95%

• Off-band (major emission lines of artificial light pollution) transmission is 0.1%

• High-value transmission of pass-band and optical density of off-band is assured through Optolong’s planetary rotation system, a homogeneous and precise coating procedure

• Each filter comes with a plastic case with high-pressure EVA case lining

• Thin metal cells have a clear aperture of 45mm for 2” filters

About Optolong

Optolong is the Astronomy Filters division of Yulong Optics, an optical filter design, and processing company out of Kunming, China that has provided filters for over 700 optical companies since 1999. All Optolong filters pass European Union RoHS requirements and have been certified by TUV Rheinland and Bureau Veritas.