The CLS (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 lightings including mercury vapour lamps, both high & low pressure sodium vapour lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Together with the highly transparent in main nebula emission lines at OIII(496nm and 500nm), H-beta (486nm), NII(654nm and 658nm), H-alpha(656nm) as well as SII(672nm), the filter is suitable for enhancing the contrast and details for both visual and photographic purpose at sub-rural area.
Suitable for colour CCD cameras and unmodified DSLRs.
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 Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.
Optolong CLS Spectrum and Characteristic
- Substrate: Optical glass
- Thickness: 1.85mm
- Tave: T>90%
- Blocking range: 400-700nm
- Blocking depth: light pollution line blocking >99%
- Surface quality: 60/40
- Transmitted Wavefront RMS: λ/4
- Parallelism: 30s
- Multi-layers anti-reflection coating
- Non-cementing optical substrate coating
- Optolong filter adopts precision coating based on Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change.
- Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band.
- About colour: due to the influence of ambient light, colour difference of the display and flash photography, the colour of the product may have some colour difference. Detailed colour is in accordance with the final product.
- About coating: the interference filter will show different colours under different light, which is a normal phenomenon. Please refer to the material object.
- About the style: in order to improve the product, the change of design/appearance/parameters has not been updated in time. Please see the subject produce.
- About the description: the series of this product have the same material, technology and design, different sizes only, please note.
What's in the Box
- Outer Box: sliver box
- Plastic Box: PP material
- Lining: imported high pressure white EVA material