Astronomik CLS Light Pollution Filter - 2" Round UnmountedThe Astronomik CLS is an excellent filter for black & white and color imaging of nebulae, galaxies and star clusters with astronomical instruments of any size. By blocking the spectral lines of mercury and sodium-vapor lamps, and letting the largest part of the visible light and H-alpha emissions pass, the CLS filter will effectively block out most surrounding light pollution, eliminating that annoying orange glare.
The filters are optimized for use with filter to aperture ratios of 1:3 to 1:15. By remaining within these aperture ratios, aberration and comma are eliminated.
Astronomik CLS Light Pollution Filter - Transmission Information...
- 92% transmission at 486nm (H-beta)
- 92% transmission at 496nm (OIII)
- 92% transmission at 501nm (OIII)
- 97% transmission at 656nm (H alpha)
- Pass from 450 to 540nm and beyond 650nm
- Parfocal with other Astronomik filters
- Glass thickness: 1mm
- Highly resistant against high humidity, scratches and aging effects
- Diffraction limited, the filter will not reduce the optical performance of your telescope!
- Astronomik filters are delivered in a high-quality, long lasting, filter box
The Astronomik CLS is our inexpensive solution for the visual deep-sky observation, b&w photography and CCD observation. The Astronomik CLS filter is the right filter to gain the contrast of nearly all objects under light-polluted skies with all sizes of telescopes. Due to the design of the transmission curve the filter reduces the sky background and gas nebulae planetary nebulae as well as open clusters, globular clusters and galaxies are seen better. The Astronomik CLS blocks the emission of Hg and Na streetlights as well as all Skyglow-lines . All major emission lines from deep-sky objects are passed without suppression. As you can see from the chart below the most important part of the eye's night-sensitive region is passed with maximum transmission. The filter are optimized for the use with focal ratio from 1:4 to 1:15. Loss of transmission and color displacements, that appear at other filters, emerge with the Astronomik filters only at extreme fast focal ratios of 1:2 and bigger. Compared to the 'Deep-Sky' filters sold by other manufacturers the Astronomik CLS shows you more stars and more details in the nebulae. Because of the high quality of the glass you will see stars as the small pinpoints you know from your scope. The Astronomik CLS can be used with all sizes of instruments. Even the use in front of binoculars is a great improvement. * High transmission of nearly 100% between 450nm and 530nm * transmission of ca 96% at H-alpha * total blocking of all unwanted light from light-pollution * the ideal all around filter for deep-sky observing, even with small scopes * completely resistant against high humidity and scratches * highest optical quality on the market