Altair Sii Oiii DualBand 6nm CERTIFIED CMOS Filter & test report

Product code: F200DB6NM-SII-OIII
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£199.00 UK Price
£165.83 (ex. VAT) International Price
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Product information

Altair Dual-Band ULTRA Sii / Oii narrowband filter with a tight 6nm FWHM Bandpass. Available in 2" or 1.25" sizes. 

Individual spectrographic test report included with each filter - another Altair first.
Available in 1.25" or 2" standard astronomy filter sizes, please choose size when ordering.

Altair V2 coatings are very effective for LED light pollution, with a deeper blocking factor of OD>6 for wavelengths below 440nm, and OD5 for the visual range.

Based on an average sample of 90 filters tested, the Bandwidth at FHWM for Oiii is 6nm with 93% transmission, and the FWHM for Sii is 5.5nm with 93% transmission. Tolerances are 0.5nm and 0.5% respectively.

This is the filter for imaging in moonlight or light pollution with a colour CMOS camera - or even in dark-sky conditions if you want total isolation and control over your channels, narrowband-style.

In a process pioneered by Altair, each individual filter in our certified range has an individual spectrographic test report with 0.1nm true resolution, unique to that particular filter. This is not a simulation, nor the overly optimistic marketing you tend to get with foreign filters - such as those advertised at 5nm FWHM but which actually have 6-7nm FWHM, and which have generic test reports.

The DualBand Ha/Oiii filter transmits only the Sii and Oiii light from emission nebulae, with almost total suppression of unwanted light, with OD5 (0.001%) over the majority of unwanted visual wavelengths. Narrowband Bi-Colour imaging is a growing new trend in astrophotography, especially popular in light polluted areas, or bright moonlight. First, Altair brought you the TriBand and Quad Band filters, now we have the DualBand Ultra for the most extreme signal vs. background performance.

Here's an overview of wavelengths transmitted by DualBand filters:

DualBand Sii Oiii 
(this filter)
DualBand Ha Oiii
Ha No Yes
Sii  Yes No
Oiii Yes Yes Bonus! You get 2x the Oiii Data when both filters are used together!

Altair DualBand 6nm Filter Features:

  • Capture the two main emission nebulae bands at the same time, whilst suppressing light pollution, moonlight, and airglow.
  • Acquire more data in less time, opening up your imaging window, even into the summer months when it isn't quite dark.
  • If you have the 6nm Sii Oiii Ultra filter and the Ha Oiii version, you can capture twice the Oiii data in each imaging session and combine them for true SHO Hubble style imaging with a colour camera!
  • Extremely steep bandpass yields maximum contrast in extreme light pollution: 6nm FHWM centred on 500.7nm Oiii wavelength, and 5.5nm FHWM centred on the 671.6nm Sii wavelength.
  • Halo suppression. We have not had any reports of halos caused by this filter in testing.
  • Can be used with One Shot Colour (OSC) CMOS or mono astronomical cameras for luminance data.
  • Includes UVIR blocking for both modified and un-modified DSLR cameras, plus an anti-reflection coating for the ultimate in contrast.
  • Best performance at focal ratios at F4.8 or slower, however can be used as fast as F3.6, with minimal contrast impact (conservative estimate - faster may be possible). Like any dichroic filter, contrast increases as focal ratio number increases. More info about light pollution filter performance and focal ratio here.
  • Available in 1.25" or 2" standard astronomy filter sizes. The filters have standard Astronomy compatible filter threads, and fit inside the Altair Magnetic Filter holders (with appropriate slider), and standard astronomy filter wheels. Choose the 2" version for use with the Altair Canon / Nikon DSLR lens to astro CMOS adaptors. For Hypercam 183C and 533C or 533M, 585C and smaller sensors choose the 1.25" filter. For larger sensors choose the 2" version.

Altair 6nm DualBand ULTRA Filter Specifications:

  • *1st band, Oiii CWL 500.7nm FWHM 6nm ~0.5nm tolerance , T% 93% 0.5% Tolerance.
  • *2nd band, Sii CWL 671.6nm FWHM 5.5nm ~0.5nm tolerance, T% 93% 0.5% Tolerance.
  • OD5 Blocking (0.001%) over unwanted visual wavelengths
  • 1.85mm thick optical glass with 30 arc sec parallelism. Parfocal with other Altair filters.
  • Si02 "hard" overcoat with UVIR Block and Anti-Reflection Coating for durability.

Q: How do OSC Narrowband filters work? Altair OSC narrowband filters work by isolating the primary nebulae emission zones in the red and blue wavelengths, and separating them into two main "zones" with a wide separation for easy capture with a colour camera - all in one exposure! Not only is capture more convenient with one filter, but processing is easy too, thanks to the wide separation of the green/blue and red "zones". Light pollution control is extremely effective and even LED light pollution is significantly reduced.

Q: What does "DualBand" mean? Here's an article explaining what a DualBand light pollution filter is

Q: What cameras are compatible with DualBand light pollution filters? Sensitive OSC or "One Shot Colour" CMOS cameras like the Altair Hypercam capture light from emission nebulae very efficiently, and allow them through the Bayer matrix, and are mostly used with Dual Band filters. These filters also work with DSLRs or in fact any colour camera! 

PLEASE NOTE: Demand for this product is very high. We sometimes temporarily suspend order to allow production to catch up. When we catch up with backorders we will re-enable ordering. We apologize for any inconvenience. Altair and Dealers reserve the right to change product specification and price without notice.

USA customers can also buy this filter from Land Sea and Sky in Texas, APM Germany and Pierro Astro in France.

Product Info

GTIN 0784300952596
Brand Altair
Product Code F200DB6NM-SII-OIII
Delivery Weight Package