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Astrodon Filters

  • Standard sizes are 1.25", 31mm, 50mm round, and 50mm square. The 1.25" is 27.5 mm of filter glass mounted in a 1.25" filter cell. The 31mm is 27.5mm of filter glass mounted in a 31mm ring. More information here: Unlike other Astrodon filters, the Photometric filters (Johnson-Cousins and Sloan) do not come as 36mm of unmounted glass. For those who want 36mm round for use in a 36mm filter wheel, 27.5 mm of filter glass can be mounted in our 36mm adapter. More information on 36mm mount here: We also have a limited quantity of 12mm and 25mm (call for pricing and availability). 100%-Coated for long-term durability and consistency of research with the highest throughput.
  • Standard sizes are 1.25", 31mm, 50mm round, and 50mm square. The 1.25" is 27.5 mm of filter glass mounted in a 1.25" filter cell. The 31mm is 27.5mm of filter glass mounted in a 31mm ring. More information here: Unlike other Astrodon filters, the Photometric filters (Johnson-Cousins and Sloan) do not come as 36mm of unmounted glass. For those who want 36mm round for use in a 36mm filter wheel, 27.5 mm of filter glass can be mounted in our 36mm adapter. More information on 36mm mount here: We also have a limited quantity of 12mm and 25mm (call for pricing and availability). 100%-Coated for long-term durability and consistency of research with the highest throughput.
  • H-α (hydrogen-alpha) at 656 nm (nanometers) is deep red in color and the most popular narrowband filter. Hydrogen is ubiquitous in the cosmos and is present in emission nebula (North American, Pelican), planetary nebula (Dumbbell, Ring), Wolf-Rayet objects (Crescent, Thor’s Helmet) and supernova remnants (Veil). Many imagers like to present just a black-and-white H-α image of an object. It is has a beauty all by itself, like an Ansel Adams photo. However, most imagers blend their H-a data into their red RGB data to enhance structural detail while maintaining a “natural” look. Therefore, the H-α filter should be your first narrowband addition to your LRGB filters. The basic imaging set of 5 filters becomes LRGBH-α.
  • SIMPLIFY YOUR IMAGING! Astrodon LRGB Gen2 E-Series Tru-Balance Filter Sets were designed for cameras containing the full-frame KAF8300, KAF3200, KAF6303, KAF16200, KAF16803 sensors, as well as most Sony and back-thinned sensors and other cameras with Progressive Scan, Front Illuminated or Back Illuminated Sensors.
  • The next filter to complement your LRGBH-a set is an oxygen filter. OIII (“ohthree”) emits light near 500 nm and is a blue-green- or teal-colored filter. Many of my images of planetary nebula and supernova remnants are taken only with H-a and OIII filters. They show great structural detail, but have natural colors, looking like an RGB image.
  • If you want the look of Hubble Space Telescope (HST) images, such as the famous “Pillars of Creation” (the Eagle Nebula, Messier 16), then the next filter to consider adding to your collection after H-a and OIII is the SII (es-two) or sulfur filter. The SII filter, like H-a, is a deep red filter near 672 nm. H-a, OIII and SII filters provide that Hubble look for many emission nebula. Again, tri-color narrowband imaging with these three filters can be done with the moon up, so your equipment is not sitting dormant for several weeks.
  • H-α (hydrogen-alpha) at 656 nm (nanometers) is deep red in color and the most popular narrowband filter. Hydrogen is ubiquitous in the cosmos and is present in emission nebula (North American, Pelican), planetary nebula (Dumbbell, Ring), Wolf-Rayet objects (Crescent, Thor’s Helmet) and supernova remnants (Veil). Many imagers like to present just a black-and-white H-α image of an object. It is has a beauty all by itself, like an Ansel Adams photo. However, most imagers blend their H-α data into their red RGB data to enhance structural detail while maintaining a “natural” look. Therefore, the H-α filter should be your first narrowband addition to your LRGB filters. The basic imaging set of 5 filters becomes LRGBH-α.
  • If you want the look of Hubble Space Telescope (HST) images, such as the famous “Pillars of Creation” (the Eagle Nebula, Messier 16), then the next filter to consider adding to your collection after H-a and OIII is the SII (es-two) or sulfur filter. The SII filter, like H-a, is a deep red filter near 672 nm. H-a, OIII and SII filters provide that Hubble look for many emission nebula. Again, tri-color narrowband imaging with these three filters can be done with the moon up, so your equipment is not sitting dormant for several weeks.
  • Bring Out The Faint Structures In Nebulae Astrodon Narrowband filters set a new bar of performance and durability for imaging and research. We offer 5 nm and ultra-narrow 3 nm bandwidths.
  • Astrodon MMOAG Off Axis Guider

    $875.00$1,750.00
    GUIDE YOUR TELESCOPE IN FRONT OF YOUR FILTERS NEW DESIGN!! ACCOMMODATES UP TO 4 GUIDE PORTS. MOAG means Manual Off-Axis Guider. It allows you to guide your telescope to obtain sharp, round stars by guiding in front of your filters using unfiltered light in the same optical beam as your imaging camera.
  • SIMPLIFY YOUR IMAGING! Astrodon LRGB Gen2 I-Series Tru-Balance Filter Sets were designed for cameras containing the Interline KAI11002, KAI16000, sensors or other cameras with Interline Transfer Sensors.
  • NII Filter, 3nm What about NII and H-a? This is a bit complicated. It is not well known that most H-a filters pass both H-a and NII. H-a emits at 656.3 nm and NII emits most strongly at 658.4 nm (and weakly at 653.8 nm). These are very close together spectrally. Thus, most H-a filters are wide enough (e.g. 4.5 nm bandwidth and wider) to pass both emission lines as shown for the older Astrodon 6 nm filter above. Our 3 nm H-a begins to separate both emission lines and reduces the NII contribution significantly. In this example the 3nm filter only transmits 15% at the NII 658.4 nm wavelength, whereas the H-a remains unchanged. As mentioned earlier, some objects are enriched in NII, such as planetary nebula and Wolf-Rayet bubbles. The Dumbbell Nebula, M27, is a good example. The wispy clouds in the core of M27 are dominantly NII. A tricolor narrowband image is also shown below, mapping OIII to blue, H-a to green and NII to red to produce a beautiful color image. This information provides you with a choice based upon your light pollution, desire for more detail, or simply wanting all the photons you can get out of your H-a filter.
  • Astrodon introduced the ExoPlanet-BB filter for use in amateur-scale telescopes to measure light curves of exoplanets.
  • GUIDE YOUR TELESCOPE IN FRONT OF YOUR FILTERS NEW DESIGN!! ACCOMMODATES UP TO 4 GUIDE PORTS. MOAG means Manual Off-Axis Guider. It allows you to guide your telescope to obtain sharp, round stars by guiding in front of your filters using unfiltered light in the same optical beam as your imaging camera.
  • UV/NIR-blocked filter used for both E- and I-Series LRGB sets. Transmits at least 97% between 400 and 700 nm. 395 nm cut-on (50% transmission at 395 nm); blocked above 705nm.
  • Astrodon Clear Filters

    $150.00$320.00
    UV-Blocked Clear filters with 395 nm cut-on (50% transmission at 395 nm) and at least 97% transmission to 1000 nm. Often purchased with our photometric filters.
  • H-α (hydrogen-alpha) at 656 nm (nanometers) is deep red in color and the most popular narrowband filter, and this 20nm H-α is the same formulation but in a wider bandpass. Hydrogen is ubiquitous in the cosmos and is present in emission nebula (North American, Pelican), planetary nebula (Dumbbell, Ring), Wolf-Rayet objects (Crescent, Thor’s Helmet) and supernova remnants (Veil). Many imagers like to present just a black-and-white H-α image of an object. It is has a beauty all by itself, like an Ansel Adams photo.
  • SIMPLIFY YOUR IMAGING! The E-Series filters were designed for cameras containing the full-frame KAF8300, KAF3200, KAF6303, KAF16803 sensors. They are also a good choice for the latest Sony and back-thinned sensor or any Progressive Scan Sensor, Front Illuminated or Back Illuminated.
  • ASTRODON UVENUS FILTER
    • <0.01%T 285-305 nm; <0.1%T 420 – 1100 nm
    • Image the cloud structure of Venus and Jupiter with CCD cameras on a telescope.
    • Use for general UV photography (flowers, insects, forensics).
  • GUIDE YOUR TELESCOPE IN FRONT OF YOUR FILTERS NEW DESIGN!! ACCOMMODATES UP TO 2 GUIDE PORTS. MOAG means Manual Off-Axis Guider. It allows you to guide your telescope to obtain sharp, round stars by guiding in front of your filters using unfiltered light in the same optical beam as your imaging camera.
  • This filter isolates only the hydrogen-beta line of the spectrum (486nm) in a 15nm wide bandpass.
  • SIMPLIFY YOUR IMAGING! Astrodon LRGB Gen2 I-Series Tru-Balance Filter Sets were designed for cameras containing Interline Transfer sensors.
  • For placing Astrodon 50 mm diameter filters in 52 mm threaded mounts for camera lenses.

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