SHO 2" 4nm Narrowband Filters | Astronomical Filters
ToupTek Astro SHO 2" 4nm Narrowband Filter Set
Ultra-narrow precision isolation for superior signal-to-noise ratio and exceptional Hubble Palette nebula details
Narrowband filters are essential for astrophotography. The ToupTek Astronomy SHO filter targets the three key ionized emission lines in stellar nurseries:
- SII (671.6nm)
- Hα (656.3nm)
- OIII (500.7nm)
With a narrower 4nm FWHM bandpass, it precisely transmits the target light while providing stronger suppression of urban light pollution and background gradients. This also reduces band overlap, resulting in higher signal-to-noise ratio, improved contrast, and more distinct detail. It is well-suited for creating images in the Hubble Palette.
Technical Parameters
Size
2"
Glass Thickness
2mm
Transmittance
>90%
FWHM
4nm (all channels)
Glass Material
Quartz Glass
Frame Material
Aluminum Alloy
OD Value
≥5.0
Coating Technology
IAD (Ion Assisted Deposition)
Transmission Range
SII
Central wavelength 671.6nm | FWHM 4nm
Hα
Central wavelength 656.3nm | FWHM 4nm
OIII
Central wavelength 500.7nm | FWHM 4nm
Surface Treatment: Double-sided high-precision optical polishing
Coating System Design: AR anti-reflection coating + quartz glass + precision cutoff coating layer
Key Features
Precise narrowband filters suppress background noise while highlighting elemental emission structures, revealing celestial stratification and fine details.
SII (671.6nm | 4nm FWHM):
Enhances detection of faint signals; Significantly boosts contrast when combined with Hα.
Enhances detection of faint signals; Significantly boosts contrast when combined with Hα.
Hα (656.3nm | 4nm FWHM):
Optimized for hydrogen regions; primary channel for nebular morphology.
Optimized for hydrogen regions; primary channel for nebular morphology.
OIII (500.7nm | 4nm FWHM):
Targets high-energy zones; reveals blue-green nebular details.
Targets high-energy zones; reveals blue-green nebular details.
ToupTek filters feature high-purity quartz glass substrates with >90% transmittance. They deliver exceptional blue-violet transmission and thermal stability, ideal for demanding astronomical imaging.
Using IAD (Ion Assisted Deposition) coating technology, which is more costly than conventional vacuum evaporation but produces denser and more uniform coatings that are durable, corrosion-resistant, and have superior environmental stability.
ToupTek filters use a proprietary multi-layer coating system—including single-sided cutoff, front AR coating, and edge blackening—to eliminate halos, minimize stray light, and ensure long-term durability.
All filters feature OD≥5.0 cutoff depth, blocking unwanted light to eliminate artifacts and deliver true-to-life color reproduction.
All filters feature matte black edge treatment to eliminate stray light, ensuring optimal transmittance and contrast.
- 2" filters: Feature threaded aluminum alloy frames for direct screw-in installation.
All filters use a single-piece, glue-free structure.
2": Full-frame & smaller sensors
Compatible with industry-standard filter wheels: 2": 5-hole/7-hole
Spectrum
Spectral Chart Reading Tips
- The horizontal axis represents the wavelength of light (in nm), and the vertical axis represents the light transmittance (in percentage %).
-
Blue line: SII (672.4nm) Red line: Hα (656nm) Green line: OIII (500.7nm)
- The emission nebula signal bands are mainly concentrated around 672.4nm (SII), 656nm (Hα), 500.7nm (OIII) and other bands.
- Light pollution peaks are commonly found near 540nm and 590nm (sodium lamp/mercury lamp bands).
The transmission regions of the astronomical filters in the spectrum avoid major interference bands to ensure effective signal passage, enhancing contrast and image purity.
ToupTek Astro SHO Narrowband Filter Performance
IC5070
Photographer: voice
Telescope: Sky-Watcher
Mount: UMI
Camera: ToupTek Astro ATR2600M
Filters: ToupTek Astro LRGB&SHO
Integration: SII: 30×600s; Hα: 30×600s; OIII: 30×600s
Total exposure: 15h
IC 443
Photographer: voice&免贵姓姚
Telescope: Sky-Watcher F3.4
Camera: ToupTek Astro ATR2600M/ATR2600C
Mount: UMi
Filters: ToupTek Astro SHO 4nm
Processing: Narrowband combination using HSO channel mapping
Total exposure: 20h
NGC2237
Photographer: 原上行川
Telescope: Askar SQA55
Camera: ToupTek Astro ATR2600M
Mount: iOptron HAE16C
Filters: ToupTek Astro SHO
Astrophotography wireless controller: StellaVita
Integration: SII: 49, Hα: 71, OIII: 63
Total exposure: 15h
Installation
Screw directly into filter wheels—no front/back orientation needed.
Warranty and Service
Quality Assurance Inspection
Each filter undergoes pre-delivery spectral testing and rigorous screening to ensure consistent optical performance.
After-sales Policy
A two-year warranty covers manufacturing defects. ToupTek Astro offers professional technical support and usage guidance.
Technical Support
For assistance, contact our customer service or technical support through our support page:
https://touptek-astro.com/supports
Important Notes
Color Variation:
Filter coating colors may appear different under varying lighting conditions and viewing angles - this is normal optical behavior.
Product Improvements:
We continually optimize our products, which may result in minor specification and appearance updates. Please note specifications are subject to change without notice. Please refer to the physical product for final details.
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