ALTAIR DualBand ULTRA CMOS Filter 3.5nm SII OIII 2" CERTIFIED with Test Report

ALTAIR DualBand ULTRA 3.5nm SII OIII 2" CMOS Filter CERTIFIED with Test Report

Altair DualBand ULTRA 3.5nm SII OIII - Professional Narrowband Filter for Astrophotography

Product Description (long)

The Altair DualBand ULTRA 3.5nm SII OIII is a high performance narrowband filter designed for astrophotography of emission nebulae under extreme conditions of light pollution and bright Moon, even in harsh urban environments.

This filter exclusively transmits the SII (671.6 nm) and OIII (500.7 nm) spectral lines, almost completely blocking the rest of the unwanted visible spectrum, with an average OD6 blockage (0.0001%), resulting in maximum contrast and exceptional signal-to-noise ratio.

It is especially effective with color CMOS cameras (OSC), although it can also be used with monochrome cameras as an advanced luminance filter for nebulae.

uLTRA Technology: absolute signal control

Thanks to its extremely narrow bandpass of only 3.5 nm (FWHM), the DualBand ULTRA offers:

• Simultaneous capture of SII + OIII in a single exposure

• Drastic reduction of light pollution, moonlight and airglow

• Possibility to take advantage of nights that are not completely dark, extending the capture window even in summertime

• More useful signal in less time

This two-color narrowband approach is currently one of the most effective techniques in modern astrophotography, especially in urban skies.

📊 Individual spectrographic report (real advantage, not marketing)

Altair is one of the few manufacturers to provide an individual spectrographic report for each filter, made with professional spectrograph at 0.1 nm resolution.

✔️ It is not a generic batch report
✔️ It is an actual measurement of the filter you buy
✔️ It guarantees exact compliance with specifications

This makes a clear difference compared to other manufacturers in the market.

✨ Key features

• 3.5 nm ultra narrow bandpass (FWHM) for maximum contrast

• Simultaneous capture of SII and OIII

• Ideal for extreme light pollution and bright Moon

• Anti-reflection coating for halo suppression

• Integrated UV/IR blocking, compatible with modified and unmodified cameras

• 1.85 mm parfocal optical glass with 30 arcsec parallelism

• Compatible with:

  • OSC CMOS cameras

  • Mono cameras (as narrowband luminance)

  • APS-C DSLRs (modified or standard)

🔧 Mechanical compatibility

• 2" format with standard thread M48x0.75

• Compatible with:

  • 2" filter holder wheels

  • Altair magnetic filter holders

  • Altair adapters for Canon / Nikon to astronomical CMOS cameras

📐 Technical Specifications - DualBand SII OIII

• OIII

  • Center length (CWL): 500.7 nm

  • FWHM: 3.5 nm ±0.2 nm

  • Transmission: 90-95 %

• SII

  • Central length (CWL): 671.6 nm

  • FWHM: 3.5 nm ±0.2 nm

  • Transmission: 90-95 % Transmission: 90-95 % Transmission: 90-95 % Transmission: 90-95 % Transmission: 90-95 % Transmission: 90-95

Common specifications:

• Average blocking: OD6 (0.0001%)

• SiO₂ hard coating

• Integrated UV/IR Cut

• Individual spectrographic report included

🧠 How do narrowband OSC filters work?

Altair narrowband OSC filters isolate the main emission lines of nebulae and separate them into two very distinct spectral zones, perfectly capturable by the color sensor Bayer array.

This allows:

• Single exposure capture

• Easier processing

• Highly effective reduction of LED light and urban pollution

differences between Altair OSC filters

⚠️ Important information

This product is manufactured in small series and demand is very high. At certain times, Altair may temporarily suspend orders to absorb production delays.

Specifications and prices are subject to change without notice.

ALTAIR DualBand ULTRA CMOS Filter 3.5nm SII OIII 2" CERTIFIED with Test Report