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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Optolong SII 3nm Narrowband Filter
Optolong SII 3nm Narrowband Filter
Optolong SII 3nm Narrowband Filter
Optolong SII 3nm Narrowband Filter

Optolong SII 3nm Narrowband Filter

by Optolong
SKU OPT-14202
$339.00 - $419.00
$419.00
$339.00 - $419.00
$419.00
Price Match Policy!
  • Isolates the Sulfur-II (SII) emission line for astrophotography
  • Extremely narrow 3nm bandpass for maximum contrast
  • Drastically reduces skyglow and common light pollution sources
  • Advanced ion-assisted anti-reflection coatings
  • Available in 2" mounted or 36mm unmounted formats
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Optolong SII 3nm Narrowband Filter

    The Optolong SII 3nm Narrowband Filter isolates the critical Sulfur-II emission line with an extremely tight 3nm bandpass. This precision dramatically increases contrast against even severe light pollution, darkening the sky background to reveal the faintest structural details in emission nebulae that wider filters cannot resolve. By passing only a 3nm sliver of the spectrum, the filter effectively eliminates interference from mercury vapor, sodium vapor, and natural skyglow.

    The 3nm Bandpass: Isolate Signal and Suppress Light Pollution

    An ultra-narrow 3nm bandpass is the key to pulling faint nebula signal out of a bright sky. Compared to wider 7nm or 12nm filters, the 3nm design provides a significant boost in signal-to-noise ratio. This allows for longer sub-exposures from urban or suburban locations, capturing deep data that would otherwise be lost in the glare.

    The "S" in SHO: Building a 3nm Hubble Palette

    The SII 3nm filter is an essential component for creating false-color Hubble Palette images. It captures the light emitted by ionized sulfur, which is typically mapped to the red channel in an SHO (SII, H-alpha, OIII) composite. This data reveals unique structures within star-forming regions and supernova remnants, adding depth, dimension, and scientific context to your final image.

    Ion-Assisted Coatings for 3nm Thermal Stability

    Maintaining a precise 3nm bandpass requires advanced coating technology. Optolong utilizes an ion-assisted deposition process to create hard, scratch-resistant coatings that are exceptionally stable. This ensures the filter's central wavelength does not drift with temperature changes during an imaging session, preventing signal loss and guaranteeing consistent results from dusk until dawn.

  • What is the main benefit of the Optolong SII 3nm filter over a wider 7nm version?

    The primary benefit of the 3nm bandpass is significantly higher contrast and better light pollution suppression. By blocking more of the unwanted skyglow, the 3nm filter produces a darker background and makes faint nebula details stand out more clearly, especially from urban or suburban locations.

    How does the Optolong SII 3nm filter perform on the Soul Nebula (IC 1848)?

    For a target like the Soul Nebula (IC 1848), the Optolong SII 3nm filter is excellent for isolating the delicate structures traced by ionized sulfur. This signal is often fainter than the dominant H-alpha, and the high contrast of the 3nm filter is crucial for capturing the wispy details and separating them from the background starfield, forming the basis of the red channel in a Hubble Palette image.

    Can I use the Optolong SII 3nm filter with a color camera?

    While designed for monochrome cameras, you can use the Optolong SII 3nm filter with a one-shot-color (OSC) camera. However, because the camera's Bayer matrix only allows a fraction of the pixels (the red ones) to detect the SII signal, the resulting image will have lower resolution and require much longer total integration time compared to using a monochrome sensor.

    Is the Optolong SII 3nm filter suitable for imaging from a Bortle 8 zone?

    Yes, absolutely. The Optolong SII 3nm filter is specifically designed for conditions like a Bortle 8 or 9 sky. Its extremely narrow 3nm bandpass aggressively rejects common sources of artificial light pollution, allowing you to capture clean narrowband data even from the middle of a city.

    What role does the Optolong SII 3nm filter data play in a final Hubble Palette image?

    In the standard SHO Hubble Palette, data from the Optolong SII 3nm filter is assigned to the Red channel. H-alpha data is assigned to Green, and OIII data is assigned to Blue. The SII signal often highlights the shock fronts and outer edges of nebulae, providing the warm golden and reddish hues that define the iconic Hubble look.

    Does the central wavelength of the Optolong SII 3nm filter shift with temperature?

    No. The Optolong SII 3nm filter is manufactured with an ion-assisted deposition coating process. This creates a very stable filter that ensures the central wavelength (CWL) does not deviate due to temperature changes during your imaging session, leading to more consistent data collection.

  • Filter Type Narrowband
    Emission Line Sulfur-II (SII)
    Bandpass 3nm
    Available Formats 2" Mounted, 36mm Round Unmounted
    Coating Technology Multi-layer, anti-reflection with Ion-assisted deposition

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  • Optolong 3-Year Warranty