【IMPROVED】SII 6.5nm Narrowband Filter
Extra narrowband SII-CCD 6.5nm filter (Sulful II for CCD) is designed for nebula observation allowing 12nm bandwidth of light centered on a wavelength of 672nm through, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).
  • Description

  • Specification

1. Optolong SII 6.5nm Narrowband Introduction

Extra narrowband SIICCD 6.5nm filter (Sulful II for CCD) is designed for nebula observation allowing 6.5nm bandwidth of light centered on a wavelength of 672nm through, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow)

  • Use with H-alpha and OIII-CCD narrowband filters (SHO Set) for tricolor CCD astrophotography. Narrowband  imaging  with  SHO  set  (H-alpha, OIII-CCD  and  SII-CCD)  can  be  done  with  the moon   up   in   heavy   light   pollution,   so   your equipment  is  not  sitting  dormant  for  several weeks.
  • Hubble look of images can be made by the combination of H-alpha, OIII-CCD and SII-CCD, such as the famous “Pillars of Creation” (M16 Eagle Nebula).
  • Narrowband filter do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.


2. Referance Spectrum



How to read the chart?

▲The horizontal axis is the Wavelength in Nanometers(nm).

▲The vertical axis is transmission in %.

▲The GREEN line shows the transmission of the OIII6.5nm filter. The H-Alpha7nm line is shown in  RED. And the SII6.5nm line is shown in BLUE.


3. Improved SII6.5nm Narrowband Filter Feature

Optolong SII6.5nm Filter Specifications Applicable Model Unit Price in US$
1.25" /1 1/4" mounted) M28.5*0.5 $159
2" mounted M48*0.6 $250
31mm unmounted CCD filter wheel $193
36mm unmounted CCD filter wheel $199




4. Manufacturing Technology

⭐High-precision grinding and polishing to make sure the substrate parallelism is greater than 30" and the surface accuracy is better than λ/4 ;

⭐Purified water ultrosonic clearning is aim to effectively remove impurities and dust from the substrate surface.

⭐Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change; IAD not only consolidates membrane compactness, increases film firmness, but also changes vacuum coating material characteristics.

⭐Planetary rotation system offers precision and homegeneity of coating ensuring high value on transmission of pass-band and Optical density of off-band;

⭐Non-cementing optical substrate coating;

⭐Quality Control: each filters is examined by Spectrophotometer for spectrum characteristic, and Laser Interferometer for surface accuracy.



5. Packing

2019 NEW package

※Note:We are now in the transition from the old to the new packaging style, ship is random.




6. Filter Performance

I.  IC 5068, from Chuck's Astrophotography/ Chuck Ayoub

"IC 5068 can be found right below the North America and Pelican nebula. I captured 16.8 hours on this target with Optolong improved narrowband filters and processed it in the Hubble Palette.
Optolong Ha: 90x240"
Optolong OIII: 87x240"
Optolong SII: 75x240"


II. Heart and Soul Nebula,  from Andrea Andreotto Maggi Astrophoto

Heart and Soul Nebula
Camera Qhyccd 600
Telescope 70 mm f 5
Filter Optolong Astronomy Filter Narrowband
12 Light 600 sec HA
12 Light 600 sec OII
12 Light 600 sec SII
Software APT - Astro Photography Tool Pixinsight Photoshop



III. Rosette nebula, by Mike Christiansen

Rosette nebula taken over several nights in the Hubble palette SHO. Taken with my QHY183M camera using my AstroTech AT80EDT apo and a 0.8 focal reducer and Optolong narrowband filters



IV. Part of IC1848.The Soul Nebula, shot by Francesco Battistella

Technical Information:

Telescope: AIRY APO 130T PrimaLuceLab
Mount: NEQ6-Pro
Camera : QHY9 -- -20°C
Filter: Optolong H-a 7nm, OIII 6.5nm, SII 6.5nm
Frames: H-a: 32x900s -- OIII: 32x900s -- SII:32x900s
Total Integration: 24 Hours
Software: SGP – PHD2 – DSS – PixInsight – CS6
Location: Noventa di Piave (Venice) 4 meter above sea level – ITALY
Environment Temperature: About 10°C
Relative Humidity: 90%
Date: 25.10.19 - 26.10.19 - 27.10.19 - 31.10.19 - 01.11.19


V. Gamma cygnus to Crescent Nebula SHO, by José Jiménez

Gamma cygnus to Crescent Nebula SHO
Sky Watcher mount AZ GTI
Canon 6D mod & WO SpaceCat51
12x600 ISO3200 Optolong Astronomy Filter H-alpha
12x600 ISO3200 Optolong Astronomy Filter SII
12x600 ISO3200 Optolong Astronomy Filter OIII



Warm Reminder:

  • About Color: The package may different due to different photography environment, lighting. What you have seen in the picture is absolutely what it is being. You might feel somewhat of color different subject to the monitor and camera, please refer to the material item.
  • About Coating: The interference items will show rich colors in different light environment, which is normal phenomenon.
  • About Product Object: Product specifications may change to improve product quality, and that updates to the specifications will be published as soon as possible.
  • About Product Overview: Please note that H-Alpha 7nm filter with same design, same raw material . Size is the only difference.

Optolong SII6.5nm features 4 sizes:

★1.25"(1 1/4" mounted), 2" mounted for eyepiece

★Round 31mm unmounted, 36mm unmounted for filter wheel