Open Box Astronomik 1.25" 6nm Narrowband Filter Set UT-11825-SoldAstronomik MFR Narrowband Emission Line Filter Highlights:
- Special Coatings Allow Filter Use Across Most Focal Ratios: Astronomik Narrowband Emission line filters have been designed to be used with a wide range of focal ratios. The special MFR (multi-focal ratio) coatings applied to the 12 nm FWHM filters make them compatible with optics as fast as f/3, and the 6 nm models perform well with focal ratios as fast as f/4. This means you won't need to buy different filters for your fast refractor and your SCT, and you won't have to pay premium prices for high-speed filters.
- Amazingly High Out of Band Blocking: Astronomik Narrowband Emission-line Filters offer superb blocking of unwanted wavelengths, from UV up to IR. Transmission of 90-percent is guaranteed by Astronomik, but the typical transmission can be as high as 96-percent on both 6 nm and 12 nm Narrowband filters. This feature translates to extremely high contrast and pleasingly dark background skies, even under heavily light-polluted conditions, allowing you to take longer exposures if you so desire without creating an overly bright (or saturated) background. Another benefit of good out-of-band blocking is the reduction of stray light and halos. Stars display as sharp points of light on a velvety black background, providing the perfect backdrop for the deep-sky object you are imaging.
- Image During Full Moon or Under Light Polluted Skies: Because Astronomik Narrowband Emission Line Filters have a high transmission rate for the chosen wavelength but blocks pretty much everything else, you can image from your own backyard, even if your neighborhood suffers from light-pollution (which is pretty much everybody). If it is a beautiful night with great seeing but the Moon phase does not support visual deep-sky astronomy, you can pull out your telescope, camera, and Astronomik filters and still get great results.