ToupTek SHO Filters (Hα / SII / OIII)

If emission nebulae are your thing (and let’s be honest… they should be), a good SHO narrowband set is the shortcut to cleaner data, higher contrast, and those classic “Hubble palette” color mixes—especially when you’re imaging under light pollution or bright skies. ToupTek’s SHO filters are precisely tuned to the key nebular emission lines and built on quartz glass with modern IAD coatings for strong transmission, tight band control, and serious out-of-band blocking.

• Complete SHO narrowband set for emission nebula imaging and Hubble-style color synthesis
• Targets the three main ionized emission lines in star-forming regions:
  • Hα (656.3nm) for nebula structure and morphology
  • OIII (500.7nm) for high-energy excitation zones and blue-green detail
  • SII (671.6nm) for faint sulfur structure and stratification (great paired with Hα for contrast)
• Dramatically reduces light pollution and background stray light, boosting signal-to-noise and contrast
• High transmission (>90%) to keep exposures efficient
• Strong out-of-band suppression with OD ≥ 5.0 blocking
• Glue-free, single-piece structure for stability and clean optical performance
• Precision optics: quartz glass + double-sided high-precision polishing
• Advanced coating stack using IAD (Ion Assisted Deposition) for durable, consistent performance
• Choose the size that matches your camera and wheel:
  • 36mm unmounted: recommended for APS-C and smaller
  • 1.25" mounted: recommended for 1-inch and smaller sensors
  • 2" mounted: recommended for full-frame and smaller
• Wide filter wheel compatibility (common patterns): 7-hole 36mm, 8-hole 1.25", 5-hole 2" electric filter wheels

Specifications

• Filter set: Hα / SII / OIII
• Available sizes: 36mm (unmounted) / 1.25" / 2"
• Glass thickness: 2mm
• Central wavelengths:
  • Hα: 656.3nm
  • SII: 671.6nm
  • OIII: 500.7nm
• Peak transmittance: >90%
• FWHM (bandwidth):
  • 36mm: 4nm (Hα 4nm / SII 4nm / OIII 4nm)
  • 1.25" & 2": 6.5nm (Hα 6.5nm / SII 6.5nm / OIII 6.5nm)
• Optical material: Quartz glass
• Cell/frame material: Aluminum alloy (for mounted sizes)
• Surface treatment: Double-sided high-precision optical polishing
• Coating technology: IAD (Ion Assisted Deposition)
• Coating design: AR anti-reflection coating + quartz glass + precision cutoff coating layer
• Optical density (blocking): OD ≥ 5.0
• Construction: Single-piece, glue-free structure
• Filter wheel compatibility (common patterns): 7-hole 36mm, 8-hole 1.25", 5-hole 2"