- Fast Shipping, Same or Next Day: You made the commitment to purchase, now you want that new item fast, we get it! At High Point all in stock orders ship within 24 hours, pending internal credit card approval.Read more ...
- Unlimited Tech Support Forever: One of the many perks of being a High Point customer is that you get access to our tech support team forever! We are astronomers at heart and truly enjoy helping fellow amateurs achieve success in the field! Read more ...
- 30 Day Return Policy: Ordered the wrong product? Don't worry, we'll take the majority of our products back within 30 days of the purchase date.We want to get you into the observing setup that bests fits your needs. Read more ...
- Guaranteed Price Match: Call or email us if you find a better price on a product! Provide a link for our team to confirm the price and within a matter of seconds you'll have a price match providing the re-seller is within the USA and authorized by the manufacturer to sell the product of interest. Read more ...
- We're Your Connection To The Manufacturer: In the event there is a warranty issue with a product purchased from High Point, we will serve as the liaison between you and the Manufacturer. The net result is faster, more attentive service from the Manufacturer and an enhanced customer experience. Read more ...
Optolong CLS Filter - 2" Mounted - CLS-200
Optolong CLS City Light Suppression Broadband Filter - 2”
The Optolong CLS filter is perfect for both visual and photographic applications in areas that suffer from artificial light pollution. Since the City Light Suppression Filter has a wider pass-band than the popular UHC, or Ultra High Contrast filter, many amateur astronomers favor its use when observing in mild to moderate light pollution. The CLS filter selectively reduces 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 filter will even help reduce skyglow caused by naturally occurring neutral oxygen emissions in our atmosphere.
The Optolong 2” CLS 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 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 2" filter cell that will produce a clear aperture of 45mm.
Transmission Characteristics of CLS Filter
- 95% transmission H-Beta 486nm
- 95% transmission OIII 496nm and 500nm
- 95% transmission H-Alpha 656nm
- 95% transmission SII 672nm
- 0.1% transmission Hg at 435nm and 578nm
- 0.1% transmission Na at 589nm
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 has 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 homogenous and precise coating procedure
- Thin metal cells have a clear aperture of 45mm for 2” filters
- Each filter comes with a plastic case with high pressure EVA case lining
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.