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Explore Scientific Nebula Filter S-II 1.25-inch 12nm
Explore Scientific Nebula Filter S-II 1.25-inch 12nm
Explore Scientific Nebula Filter S-II 1.25-inch 12nm
Explore Scientific Nebula Filter S-II 1.25-inch 12nm

Explore Scientific Nebula Filter S-II 1.25-inch 12nm

by Explore Scientific
SKU ES-310115
CA$224.00 - CA$224.00
CA$224.00
CA$224.00 - CA$224.00
CA$224.00
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  • Isolates the ionized sulfur (S-II) emission line at 672nm
  • Features a 12nm bandpass to increase contrast
  • Standard 1.25-inch filter format
  • Ideal for both visual observation and astrophotography
  • Includes an individual test report for quality assurance
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Nebula Filter S-II 1.25-inch 12nm

    The Explore Scientific S-II Nebula Filter isolates a specific 12nm band of red light centered on the 672nm wavelength, targeting the emission line of ionized sulfur. This 1.25-inch filter is engineered to dramatically increase the contrast of specific deep-sky objects by rejecting light pollution from artificial sources and the unwanted glow of natural skyglow.

    Isolating the 672nm S-II Line: A 12nm Passband for High Contrast

    Many of the most sought-after deep-sky targets are emission nebulae, which glow at discrete wavelengths corresponding to their chemical makeup. This filter is designed to transmit only the light from ionized sulfur at 672nm, a key component in the structure of objects like the Eagle Nebula (M16) and the Lagoon Nebula (M8). By blocking nearly all other wavelengths, the filter renders the faint structure of the nebula against a much darker sky background.

    • 12nm Bandpass: This width is an excellent compromise, offering a significant contrast boost over broadband filters while being more forgiving for visual use than ultra-narrow 3nm or 5nm filters. It reveals details in emission nebulae, planetary nebulae, and supernova remnants that are otherwise lost to light pollution.
    • Individual Test Report: Each Explore Scientific filter includes an individual test certificate, guaranteeing that its bandpass and transmission characteristics meet the 12nm specification. This ensures you receive a filter that performs as advertised.

    A 1.25-Inch Filter for Visual and Photographic Deep Sky

    Designed in the universal 1.25-inch format, this S-II filter threads directly into standard eyepieces and filter wheels. For visual observers, it can make the difference between seeing a faint nebula and missing it entirely, especially from suburban skies. The contrast enhancement can reveal intricate wisps and structural details that are normally invisible.

    For astrophotographers, the S-II filter is a cornerstone of narrowband imaging. It allows you to capture one of the three key emission lines (along with H-alpha and O-III) used to create detailed, full-color images from even heavily light-polluted locations. Capturing S-II data is essential for producing images in popular palettes like the "Hubble Palette" (SHO).

  • What is the primary purpose of the Explore Scientific 12nm S-II filter?

    The primary purpose of this filter is to increase the contrast of emission nebulae that glow in the light of ionized sulfur (S-II). It achieves this by selectively passing a 12nm-wide band of light centered at the 672nm wavelength while blocking out light pollution and other unwanted wavelengths, resulting in a darker sky background and more visible nebular detail.

    How does the 12nm S-II filter help in light-polluted skies?

    Artificial lighting, like streetlights, primarily emits light across a broad spectrum. The Explore Scientific S-II filter blocks almost all of this light, only allowing the specific 672nm wavelength from the nebula to pass through. This effectively subtracts the light pollution from the view, making faint objects visible even from urban or suburban locations.

    Will this 1.25-inch S-II filter work with my color camera for astrophotography?

    While you can use this filter with a color camera, it is not ideal. The camera's Bayer matrix has red, green, and blue pixels, and this filter only passes deep red light that will be recorded by the red pixels. For best results, narrowband filters like this S-II are used with monochrome astronomy cameras, allowing you to capture separate data for each emission line (S-II, H-alpha, O-III) and combine them later into a full-color image.

    What objects show the most detail with the 12nm S-II filter, for example, the Eagle Nebula (M16)?

    The Eagle Nebula (M16) is an excellent target, as its famous "Pillars of Creation" are rich in ionized sulfur. Other strong S-II targets include:

    • The Lagoon Nebula (M8)
    • The Omega/Swan Nebula (M17)
    • The Rosette Nebula (NGC 2237)
    • Supernova remnants like the Veil Nebula (NGC 6960)

    I have an 8" SCT. Is a 12nm S-II filter a good choice for visual observing?

    Yes, it's a very good choice. In an 8" SCT, you have enough aperture to gather sufficient light for visual narrowband observing. The 12nm bandpass provides a strong contrast boost without making the image overly dim, which can be an issue with tighter 3nm or 5nm filters for visual use. It will help you see structure in planetary and emission nebulae that would otherwise be washed out.

    Why is an individual test report included with the Explore Scientific S-II filter?

    The individual test report is your assurance of quality control. It certifies that your specific filter has been tested and meets the advertised specifications for its central wavelength (672nm) and bandpass (12nm). This guarantees that the filter will perform as expected, effectively isolating the desired S-II emission line.

  • Explore Scientific Warranty