The 31 mm CLS Light Pollution Filter - Mounted in Low Profile Non-Threaded Cell by Astronomik:
The 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.
Now Mounted in Low Profile Non-Threaded Cell: Sometimes unmounted CCD filters can be hard to handle. The smaller diameters, such as this 31 mm CLS filter, can be especially difficult to pick up and insert or remove from the filter wheel, and that can lead to possible damage as well as unwanted reflections from incorrectly installed filters. Astronomik has solved this problem by mounting their 31 mm and 36 mm filters in a low profile (3 mm) non-threaded cell. O-rings, washers, or spacers are no longer required to hold the filter in place, and because the cell is only 3 mm thick, it works well in all appropriately sized filter wheels. Mounted 31 mm and 36 mm Astronomik filters will also play nice with unmounted versions in the same carousel.
Astronomik CLS Light Pollution Filter - Transmission Information:
- 92-percent transmission at 486 nm (H-beta)
- 92-percent transmission at 496 nm (OIII)
- 92-percent transmission at 501 nm (OIII)
- 97-percent transmission at 656 nm (H-alpha)
- Pass from 450 to 540 nm and beyond 650 nm
- Parfocal with other Astronomik filters
- Glass thickness: 1mm
- Cell thickness: 3 mm
- 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
OPT Product Number: AK-CLS-31