Antlia 3nm Narrowband Sulfur II (SII) Pro Highspeed Imaging Filter for f/2.6 - f/3.6 Telescopes - 36mm Unmounted
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PLEASE NOTE: Antlia is making a running change to their packaging. They are transitioning from 2-piece magnetic plastic cases to a smaller 1-piece non-magnetic design. Depending on the item(s) you order, you may randomly get one case type or the other or a mix of the two. We cannot entertain requests for any specific case type.
IMPORTANT: Please read this important note below before buying Antlia narrowband filters. No returns will be accepted for Antlia narrowband filters exhibiting halos around bright stars as disclosed below.
Please note that some users may see halos around bright stars in images made with this filter. Such halos have been observed with filters from other leading manufacturers and in the previous generation of Antlia narrowband filters as well. These halos can be caused and/or made worse by other optical accessories in the imaging train, their relative positions, telescope design/optics, camera, software, or a combination thereof. In general, OIII filters seem to have a higher propensity to show halos compared to H-alpha or S-II filters, but in rare cases the latter filters can also exhibit faint halos around bright stars.
Antlia has made great strides in their coatings to minimize haloing of bright stars, but you may still observe this effect to some degree. See the sample OIII image below of Alnitak (magnitude 1.74) and IC434 in Orion (SkyRover 155mm Apo, ZWO 6200MM-P Camera, 20 min exposure) provided by Antlia. In most cases, haloing will not affect your image unless you have very bright stars in the field of view.
Please note we are unable to accept returns of any Antlia narrowband filters if you do observe this haloing effect in your images.
If you must ensure there are no detectable halos in your images, you may want to consider Astrodon or Chroma narrowband filters instead. These filters, however, cost two to three times as much as Antlia 3nm filters do. Antlia is being honest and upfront. They are the ones telling us about these halos, that their filters are great for the money but still not as good as Astrodon/Chroma, and pointing out that with this full disclosure, they will not accept returns. They are leaving it up to the customer to decide if this is good enough for them or not. We believe that for most imaging applications, Antlia filters continue to offer excellent value for astrophotographers and these continue to be among our top sellers.
Antlia's Sulfur II (SII) 3nm Pro Highspeed Filter is further optimized for high-speed imaging systems by pre-shifting the center wavelength. This specially-optimized version will provide significantly SNR (Signal to Noise Ratio) for the fast telescopes with focal ratio between f/2.6 and f/3.6 than the standard 3nm Pro version.
The optical light path of a telescope is cone-shaped, which creates an angle, and the center wavelength of the interference filter will shift toward shorter (blue) wavelengths as the angle of incidence((AOI) increases; the greater the angle, the greater the shift. The amount of beam deviation depends on the refractive index and the thickness of the substrate. The blue shift data by the simulation indicates that at a focal ratio of f/2.6, the angle of incidence of the light cone is 10°and its bandwidth shift 2.2nm to shorter wavelengths. Therefore, the Highspeed 3nm Pro narrowband filters are designed to be pre-shifted by 1.2nm towards the longer (red) end in order to compensate for the Blueshift and ensure high signal acquisition by telescopes with fast focal ratios.
Using this highspeed Sulfur II (SII) 3nm Pro narrowband filter for the telescopes with focal ratio between f/2.6 and f/3.6 shows much stronger and more contrasted in astronomy imaging compared to the standard Pro version.
For optics f-ratios slower than f/3.6, the standard 3nm Pro filters are highly recommended. Meanwhile, if you use optics faster than f/2.6, the 4.5nm EDGE filters are the good choice.
Features:
- High transmittance SII＞90% and 3nm bandwidth to maximize contrast
- Antlia narrowband Pro Highspeed filters can be used with focal ratio f/2.6-f3.6 systems with minimal loss of signal
- Improved sharp cut-off astrophotography 3nm Pro series filters are designed to minimize halos around bright stars
- The out of band blocking specification is rated OD5 (0.001%) which delivers an excellent SNR (signal to noise ratio) and effective cut-off rate to minimize interference from other wavelengths
- A single substrate to eliminate internal reflections
- Narrowband Objects: Emission Nebulae, Planetary, Wolf Rayet Nebulae and Supernova Remnants
- Use in light polluted areas and dark sites
- Extends imaging time when the moon is up
- All Antlia unmounted narrowband Highspeed filters are edge blackened to eliminate internal reflections from stray light
- Superior optical reliability reduces post image processing
- Basic Substrate: Optical, Single / Non-glued substrate
- Surface Quality: S/D (scratch/dig)= 60/40 (Refer to MIL-O-13830)
- Transmitted Wavefront: Lambda/4 or better.
- Parallelism: less than 30 arcsec
- Warranty: 3-years against delamination
Technical Specifications:
- FWHM: 3nm
- CWL (Central Wavelength): 673.6nm
- Peak Transmission: 90%
- Blocking: ≥OD5 @ 300-1000nm
- Filter Thickness: 2mm+/-0.05mm
Filter Ring:
- None. 36mm round diameter, unmounted
Not Recommended:
- Solar imaging
- Night visual observation
Not Permitted:
- DO NOT LOOK AT THE SUN WITH THIS FILTER
- Serious eye damage will result if you fail to observe the warning.
Other Information
- Country of Manufacture: China
Antlia's Sulfur II (SII) 3nm Pro Highspeed Filter is further optimized for high-speed imaging systems by pre-shifting the center wavelength. This specially-optimized version will provide significantly SNR (Signal to Noise Ratio) for the fast telescopes with focal ratio between f/2.6 and f/3.6 than the standard 3nm Pro version.
The optical light path of a telescope is cone-shaped, which creates an angle, and the center wavelength of the interference filter will shift toward shorter (blue) wavelengths as the angle of incidence((AOI) increases; the greater the angle, the greater the shift. The amount of beam deviation depends on the refractive index and the thickness of the substrate. The blue shift data by the simulation indicates that at a focal ratio of f/2.6, the angle of incidence of the light cone is 10°and its bandwidth shift 2.2nm to shorter wavelengths. Therefore, the Highspeed 3nm Pro narrowband filters are designed to be pre-shifted by 1.2nm towards the longer (red) end in order to compensate for the Blueshift and ensure high signal acquisition by telescopes with fast focal ratios.
Using this highspeed Sulfur II (SII) 3nm Pro narrowband filter for the telescopes with focal ratio between f/2.6 and f/3.6 shows much stronger and more contrasted in astronomy imaging compared to the standard Pro version.
For optics f-ratios slower than f/3.6, the standard 3nm Pro filters are highly recommended. Meanwhile, if you use optics faster than f/2.6, the 4.5nm EDGE filters are the good choice.
Features:
- High transmittance SII＞90% and 3nm bandwidth to maximize contrast
- Antlia narrowband Pro Highspeed filters can be used with focal ratio f/2.6-f3.6 systems with minimal loss of signal
- Improved sharp cut-off astrophotography 3nm Pro series filters are designed to minimize halos around bright stars
- The out of band blocking specification is rated OD5 (0.001%) which delivers an excellent SNR (signal to noise ratio) and effective cut-off rate to minimize interference from other wavelengths
- A single substrate to eliminate internal reflections
- Narrowband Objects: Emission Nebulae, Planetary, Wolf Rayet Nebulae and Supernova Remnants
- Use in light polluted areas and dark sites
- Extends imaging time when the moon is up
- All Antlia unmounted narrowband Highspeed filters are edge blackened to eliminate internal reflections from stray light
- Superior optical reliability reduces post image processing
- Basic Substrate: Optical, Single / Non-glued substrate
- Surface Quality: S/D (scratch/dig)= 60/40 (Refer to MIL-O-13830)
- Transmitted Wavefront: Lambda/4 or better.
- Parallelism: less than 30 arcsec
- Warranty: 3-years against delamination
Technical Specifications:
- FWHM: 3nm
- CWL (Central Wavelength): 673.6nm
- Peak Transmission: 90%
- Blocking: ≥OD5 @ 300-1000nm
- Filter Thickness: 2mm+/-0.05mm
Filter Ring:
- None. 36mm round diameter, unmounted
Not Recommended:
- Solar imaging
- Night visual observation
Not Permitted:
- DO NOT LOOK AT THE SUN WITH THIS FILTER
- Serious eye damage will result if you fail to observe the warning.
PLEASE NOTE: Antlia is making a running change to their packaging. They are transitioning from 2-piece magnetic plastic cases to a smaller 1-piece non-magnetic design. Depending on the item(s) you order, you may randomly get one case type or the other or a mix of the two. We cannot entertain requests for any specific case type.
IMPORTANT: Please read this important note below before buying Antlia narrowband filters. No returns will be accepted for Antlia narrowband filters exhibiting halos around bright stars as disclosed below.
Please note that some users may see halos around bright stars in images made with this filter. Such halos have been observed with filters from other leading manufacturers and in the previous generation of Antlia narrowband filters as well. These halos can be caused and/or made worse by other optical accessories in the imaging train, their relative positions, telescope design/optics, camera, software, or a combination thereof. In general, OIII filters seem to have a higher propensity to show halos compared to H-alpha or S-II filters, but in rare cases the latter filters can also exhibit faint halos around bright stars.
Antlia has made great strides in their coatings to minimize haloing of bright stars, but you may still observe this effect to some degree. See the sample OIII image below of Alnitak (magnitude 1.74) and IC434 in Orion (SkyRover 155mm Apo, ZWO 6200MM-P Camera, 20 min exposure) provided by Antlia. In most cases, haloing will not affect your image unless you have very bright stars in the field of view.
Please note we are unable to accept returns of any Antlia narrowband filters if you do observe this haloing effect in your images.
If you must ensure there are no detectable halos in your images, you may want to consider Astrodon or Chroma narrowband filters instead. These filters, however, cost two to three times as much as Antlia 3nm filters do. Antlia is being honest and upfront. They are the ones telling us about these halos, that their filters are great for the money but still not as good as Astrodon/Chroma, and pointing out that with this full disclosure, they will not accept returns. They are leaving it up to the customer to decide if this is good enough for them or not. We believe that for most imaging applications, Antlia filters continue to offer excellent value for astrophotographers and these continue to be among our top sellers.
Antlia's Sulfur II (SII) 3nm Pro Highspeed Filter is further optimized for high-speed imaging systems by pre-shifting the center wavelength. This specially-optimized version will provide significantly SNR (Signal to Noise Ratio) for the fast telescopes with focal ratio between f/2.6 and f/3.6 than the standard 3nm Pro version.
The optical light path of a telescope is cone-shaped, which creates an angle, and the center wavelength of the interference filter will shift toward shorter (blue) wavelengths as the angle of incidence((AOI) increases; the greater the angle, the greater the shift. The amount of beam deviation depends on the refractive index and the thickness of the substrate. The blue shift data by the simulation indicates that at a focal ratio of f/2.6, the angle of incidence of the light cone is 10°and its bandwidth shift 2.2nm to shorter wavelengths. Therefore, the Highspeed 3nm Pro narrowband filters are designed to be pre-shifted by 1.2nm towards the longer (red) end in order to compensate for the Blueshift and ensure high signal acquisition by telescopes with fast focal ratios.
Using this highspeed Sulfur II (SII) 3nm Pro narrowband filter for the telescopes with focal ratio between f/2.6 and f/3.6 shows much stronger and more contrasted in astronomy imaging compared to the standard Pro version.
For optics f-ratios slower than f/3.6, the standard 3nm Pro filters are highly recommended. Meanwhile, if you use optics faster than f/2.6, the 4.5nm EDGE filters are the good choice.
Features:
- High transmittance SII＞90% and 3nm bandwidth to maximize contrast
- Antlia narrowband Pro Highspeed filters can be used with focal ratio f/2.6-f3.6 systems with minimal loss of signal
- Improved sharp cut-off astrophotography 3nm Pro series filters are designed to minimize halos around bright stars
- The out of band blocking specification is rated OD5 (0.001%) which delivers an excellent SNR (signal to noise ratio) and effective cut-off rate to minimize interference from other wavelengths
- A single substrate to eliminate internal reflections
- Narrowband Objects: Emission Nebulae, Planetary, Wolf Rayet Nebulae and Supernova Remnants
- Use in light polluted areas and dark sites
- Extends imaging time when the moon is up
- All Antlia unmounted narrowband Highspeed filters are edge blackened to eliminate internal reflections from stray light
- Superior optical reliability reduces post image processing
- Basic Substrate: Optical, Single / Non-glued substrate
- Surface Quality: S/D (scratch/dig)= 60/40 (Refer to MIL-O-13830)
- Transmitted Wavefront: Lambda/4 or better.
- Parallelism: less than 30 arcsec
- Warranty: 3-years against delamination
Technical Specifications:
- FWHM: 3nm
- CWL (Central Wavelength): 673.6nm
- Peak Transmission: 90%
- Blocking: ≥OD5 @ 300-1000nm
- Filter Thickness: 2mm+/-0.05mm
Filter Ring:
- None. 36mm round diameter, unmounted
Not Recommended:
- Solar imaging
- Night visual observation
Not Permitted:
- DO NOT LOOK AT THE SUN WITH THIS FILTER
- Serious eye damage will result if you fail to observe the warning.
Other Information
- Country of Manufacture: China
Antlia 3nm Narrowband Sulfur II (SII) Pro Highspeed Imaging Filter for f/2.6 - f/3.6 Telescopes - 36mm Unmounted