Enhance Your Stargazing Experience with Astronomik CLS Filters - Minimize Light Pollution and Maximize Astronomical Detail. The Astronomik CLS (City Light Suppression) Filter is your ticket to clear and vivid celestial observations. Say goodbye to urban light pollution and hello to stunning views of nebulae, galaxies, and star clusters. Designed with precision and crafted for astrophotographers and astronomers, the Astronomik CLS Filter is your partner in unveiling the mysteries of the night sky. Elevate your astronomy game today!

The Astronomik CLS is a budget filter for visual observation, Black & White photography and CCD photographs of nebulae, galaxies and star clusters with astronomical instruments of any size.

The Astronomik CLS blocks the light of the spectral lines of mercury and sodium-vapor lamps and lets the largest part of the visible light and H-alpha emissions pass. All the important emission lines, as well as the spectral region that the very well dark adapted eye can see, can pass through the filter.

20s exposures with JPEG data directly out of the camera without any further processing. When the  mouse is moved over the image the image with the Astronomik CLS is shown. (Canon EOS 6D astro-modified, ISO 6400, Canon EF24-105mm f/4L IS II USM @ 24mm/4)

Main use

The filters are optimized for use with aperture ratios from 1:3 to 1:15. Transmission losses and chromatic distortions, which are problems with other filters, only appear with Astronomik filters when extremely bright aperture ratios of 1:2 and more are used. The CLS filter is suitable for use with telescopes of all aperture sizes.

Specifications

• 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
• Completely 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
• Since 2008 we do ship filters with a completely new design. Any kind of halo or strange reflection is a matter of past