• Explore Scientific S-II 7nm Narrowband Filter 1.25"
  • Explore Scientific S-II 7nm Narrowband Filter 1.25"
  • Explore Scientific S-II 7nm Narrowband Filter 1.25"
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Explore Scientific

Explore Scientific S-II 6.5nm Narrowband Filter 1.25" — Ultra-Narrow Sulfur-II Filter for Deep-Sky Imaging

Explore Scientific S-II 6.5nm Narrowband Filter 1.25" — Ultra-Narrow Sulfur-II Filter for Deep-Sky Imaging

$140.00
$199.99 $140.00
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The Explore Scientific S-II 6.5nm Narrowband Filter (1.25") isolates the deep-red light of doubly-ionized sulfur (S-II, ~672nm) with an ultra-narrow 6.5nm passband, for maximum-contrast narrowband astrophotography. The tighter bandwidth blocks even more light pollution and skyglow than a 12nm filter, so faint emission-nebula structure stands out against a very dark background.

Who it's for

Astrophotographers using monochrome cameras — especially from light-polluted skies — who want the highest contrast on emission nebulae. New to filters? See our guide to the best telescope filters for beginners.

Key features

  • Isolates the S-II line (~672nm) with an ultra-narrow 6.5nm passband
  • Maximum contrast and excellent rejection of light pollution and moonlight
  • Reveals faint nebula structure for detailed deep-sky images
  • Part of the S-II / H-Alpha / O-III set for Hubble-palette (SHO) imaging
  • 1.25" mounted and threaded for filter wheels and drawers

Specifications

Type Narrowband S-II imaging filter
Emission line S-II (~672 nm)
Bandwidth 6.5 nm
Fitting 1.25" threaded
SKU 310125

Frequently asked questions

6.5nm or 12nm?
The 6.5nm gives higher contrast and better light-pollution rejection, ideal for suburban skies and slower telescopes. The 12nm is more forgiving with fast focal ratios. Both isolate the same S-II line.

What camera do I need?
Narrowband filters are designed for monochrome astronomy cameras, combining S-II, H-Alpha, and O-III frames into a color image.

Does it work with fast telescopes?
Ultra-narrow filters perform best at slower focal ratios; very fast scopes can shift the passband slightly, so 12nm may be a safer choice below about f/4.

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Frequently Asked Questions

With a beginner telescope you can see a surprising amount — the craters and mountains on the Moon, the rings of Saturn, the moons of Jupiter, and star clusters like the Pleiades. As you get more comfortable, you can also spot nebulae and distant galaxies. Not sure which beginner telescope is right for you? Check out our Telescope Buying Guide.
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