ToupTek Astro SHO 2" 4nm Narrowband Filter Set

4 nm SHO-smalbandsfilter från ToupTek Astro stöder exakta filterbyten, LRGB- eller smalbandsbildtagning och jämna deep-sky-resultat.

Narrowband filters are essential for astrophotography. The ToupTek Astro SHO filter set 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

Storlek 2"

Glass Thickness 2mm

Transmittance >90%

FWHM 4nm (all channels)

Glass Material Quartz Glass

Frame Material Aluminiumlegering

OD Value ≥5.0

Beläggningsteknik 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

Viktiga funktioner

Precise narrowband filters suppress background noise while highlighting elemental emission structures, revealing celestial stratification and fine details.

SII SII (671.6nm | 4nm FWHM):
Enhances detection of faint signals; Significantly boosts contrast when combined with Hα.

Hα Hα (656.3nm | 4nm FWHM):
Optimized for hydrogen regions; primary channel for nebular morphology.

OIII OIII (500.7nm | 4nm FWHM):
Targets high-energy zones; reveals blue-green nebular details.

ToupTek filters feature high-purity quartz glass substrates with >90% transmittance. They deliver strong 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 improved 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.

4 nm SHO-smalbandsfilter från ToupTek Astro stöder exakta filterbyten, LRGB- eller smalbandsbildtagning och jämna deep-sky-resultat.

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

SHO 2-inch 4nm Filter Spectral Response Curves

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

Varje filter genomgår spektral testning och noggrann kontroll före leverans för att säkerställa konsekvent optisk prestanda.

After-sales Policy

4 nm SHO-smalbandsfilter från ToupTek Astro stöder exakta filterbyten, LRGB- eller smalbandsbildtagning och jämna deep-sky-resultat.

Teknisk support

For assistance, contact our customer service or technical support through our support page:
https://touptek-astro.com/technical-support

Viktiga anmärkningar

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.

ToupTek Astro SHO 2" 4nm Narrowband Filter Set