Astronomik 6 nm OIII MFR Narrowband Emissionline Filter
Mounted in Low Profile Non-Threaded 31 mm Round Cell
Astronomik OIII Narrowband Filters are suitable for false color imaging of emission nebulae emanating doubly ionized oxygen (OIII). The contrast between an object glowing at 501nm and the background is increased significantly due to the high transmission and effective out-of-band blocking!
The OIII line (501 nm) is in the blue-green portion of the spectrum. Planetary nebulae & supernova remnants are considered emission nebulae, since they produce their own light, and so objects like the Ring, Dumbbell, Veil & Crab nebulae are common targets using OIII filters since doubly ionized oxygen is the main emission for these interesting objects.
This Astronomik OIII MFR Narrowband filter has a 6 nm FWHM. The extra narrow bandpass of 6 nm filters are most appreciated with cameras that offer extremely low dark current and good cooling, or when imaging in areas with severe light pollution. The higher level of out-of-band blocking allows you to take longer exposures and choose objects imbedded in normally over-bright, crowded areas of the Milky Way. Extra blocking causes faint stars to disappear from the background, and brighter stars will be pin-pricks of light.
Now Mounted in Low Profile Non-Threaded Cell
Sometimes unmounted filters can be hard to handle. The smaller diameters, such as this 31 mm OIII 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 MFR Narrowband Emission Line Filter Highlights
- Special Coatings Allow Filter Use Across Most Focal Ratios: Astronomik Narrowband Emissionline 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% is guaranteed by Astronomik, but the typical transmission can be as high as 96% 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 haloes. 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’s a beautiful night with great seeing but the Moon phase doesn’t support visual deep-sky astronomy, you can pull out your telescope, camera, and Astronomik filters and still get great results.
Ten Year Warranty! Astronomik filters will last for many years without degradation of the coatings, due to the quality of the substrate and coatings used. The high-quality glass is optically polished and is free of stress and striae. The coatings used on Astronomik filters are applied in multiple layers, making the resulting filter scratch resistant and unaffected by moisture or aging that some filters of less quality may be prone to. Astronomik filters are also parfocal due to the small thickness tolerance allowed. Astronomik backs up this quality with a ten-year warranty.
- Additional Information
SKU AK-OIIICCD6-31 Manufacturer Astronomik Type of Filter Oxygen III Filter Usage Imaging Single or Set? Single Filter Filter Size 31mm Filter Shape Round Filter Mounted? Mounted Warranty 10 Year Warranty FWHM Bandwidth 6nm
- Included Items
- Astronomik 6 nm OIII CCD Filter with MFR Coatings - 31 mm Round Mounted
- Storage Box
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