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    ToupTek Astro

    SHO Filters

    SHO Filters

    H-alpha Filter SII Filter OIII Filter
    $179.00 USD
    $179.00 USD
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    Description
    REVIEWS
    Why Choose Narrowband Filters?
    Narrowband filters are essential accessories in astrophotography used to isolate specific wavelength emission lines and enhance the signal-to-noise ratio of your target—especially for capturing breathtaking emission nebulae.

    ToupTek HSO narrowband filters are precisely tuned to the three main ionized emission lines found in star-forming regions:
    • Hα (656.3nm)
    • SII (671.6nm)
    • OIII (500.7nm)
    By using these filters, you can effectively block urban light pollution and background stray light, dramatically enhance signal contrast, and bring out incredible detail—empowering you to achieve Hubble-like color mixing (SHO synthesis) in your astrophotography.
    HSO filters for astrophotography
    Technical Parameters
    Size: 36mm (unframed) / 1.25” / 2”
    Glass Thickness: 2mm
    Transmission Range:
    • H-alpha filter: Central wavelength 656.3nm
    • SII filter: Central wavelength 671.6nm
    • OIII filter: Central wavelength 500.7nm
    Transmittance: >90%
    FWHM:
    • 36mm: H-alpha (3.5nm) / SII (4nm) / OIII (4nm)
    • 1.25” & 2”: H-alpha (6.5nm) / SII (6.5nm) / OIII (6.5nm)
    Glass Material: Quartz glass
    Frame Material: Aluminum Alloy
    Surface Treatment: Double-sided high-precision optical polishing
    Coating Technology: IAD (Ion Assisted Deposition)
    Coating System Design: AR anti-reflection coating + quartz glass + precision cutoff coating layer
    OD: ≥5.0
    HSO filters for astrophotography
    Key Features
    ▶️ Precise Band Control & Enhanced Detail Resolution
    The precise narrowband design effectively suppresses background noise while highlighting the emission structures of different elements, resulting in clearer celestial stratification and enhanced detail gradation.

    ▲ Hα filter: Central wavelength 656.3nm, FWHM 3.5nm.
    Optimized for hydrogen ionization regions, this filter serves as the primary channel for capturing nebular morphology.
    ▲ OIII filter: Central wavelength 500.7nm (OIII emission line), FWHM 4nm.
    Designed to reveal high-energy excitation zones, particularly effective for visualizing blue-green nebular details.
    ▲ SII filter: Central wavelength 671.6nm, FWHM 4nm.
    Enhances detection of faint signals and reveals structural stratification through ionized sulfur distribution. When combined with Hα, significantly improves image contrast.
    *FWHM for 1.25-inch and 2-inch filters is 6.5nm.
    ▶️ High-Quality Quartz Glass, High Transparency and Purity
    The entire series of ToupTek Astro filters utilize high-quality colorless transparent quartz glass, with >90% high transmittance, high purity, exceptional blue-violet band transmission, and outstanding thermal stability—ideal for various demanding astronomical imaging applications.
    ▶️ IAD Dense Coating, Durable and Stable
    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.
    ▶️ Precision Coating, Significantly Suppresses Halos
    ToupTek Astro filters employ a proprietary multi-layer system: a single-sided cutoff coating, front surface AR anti-reflection coating, and edge blackening treatment. This combination effectively minimizes internal reflections and stray light while ensuring coating integrity and extended service life.
    ▶️ High Optical Cutoff Depth, Restores Natural Colors
    All channel filters have a cutoff depth of OD≥5.0, effectively blocking non-target spectral regions, avoiding band crosstalk and color cast, resulting in accurate and natural color reproduction.
    ▶️ Matte Black Edge Coating, Easy Installation
    The filter edge is coated with a black matte treatment to minimize stray light, which ensures transmittance, reduces glare, and enhances image contrast.
    ▲ 36mm filters: The telescope-facing side has an inward-extending blackened border for quick orientation identification.
    ▲ 1.25" & 2" filters: Feature threaded aluminum alloy frames for direct screw-in installation, ensuring fast and tool-free mounting.
    ▶️ Highly Compatible
    All filters use a single-piece, glue-free structure.
    ▲ 36mm: Recommended for APS-C and smaller cameras.
    ▲ 1.25": Recommended for cameras with a 1-inch or smaller sensor.
    ▲ 2": Recommended for full-frame and smaller cameras.
    Compatible with various brands on the market featuring 7-hole 36mm, 8-hole 1.25-inch, and 5-hole 2-inch electric filter wheels, offering a wider range of compatibility options.
    HSO filters for astrophotography
    Spectrum
    3.5 and 4nm HSO filter spectrum 6.5nm HSO filter spectrum
    Spectral Chart Reading Tips:
    • The horizontal axis represents the wavelength of light (in nm), and the vertical axis represents light transmittance (percentage %).
    • Red line: Hα (656nm); Green line: OIII (500.7nm); Blue line: SII (672.4nm).
    • Emission nebula signal bands are mainly at 656nm (Hα), 500.7nm (OIII), and similar wavelengths.
    • Light pollution peaks are often found near 540nm and 590nm (sodium/mercury lamp bands).
    The transmission regions of our astronomical filters are engineered to avoid these interference bands, ensuring maximum signal clarity, enhanced contrast, and high image purity for deep-sky imaging.
    ToupTek Astro HSO Narrowband Filter Performance
    IC5070
    Photographer: voice
    Telescope: Sky-Watcher
    Mount: UMI
    Camera: ToupTek Astro ATR2600M
    Filters: ToupTek Astro 36mm LRGB&SHO
    Integration: Hα: 30 × 600s ; SII: 30 × 600s ; OIII: 30 × 600s
    Total exposure: 15h
    IC5070 Sample Image
    IC443
    Photographer: voice
    Telescope: Sky-Watcher F3.4
    Camera: ToupTek Astro ATR2600M / ATR2600C
    Mount: UMI
    Filters: ToupTek Astro 36mm HSO
    Processing: Narrowband combination using HSO channel mapping
    Total exposure: 20h
    IC443 Sample Image
    NGC2237
    Photographer: 原上行川
    Telescope: Askar SQA55
    Camera: ToupTek Astro ATR2600M
    Mount: iOptron HAE16C
    Filters: ToupTek Astro 36mm HSO
    Astrophotography wireless controller: StellaVita
    Integration: Hα: 71 ; OIII: 63 ; SII: 49
    Total exposure: 15h
    NGC2237 Sample Image
    M16
    Photographer: Yahushua
    Telescope: Askar 130HNT28-AL
    Camera: ToupTek Astro ATR585M
    Mount: iOptron CEM26
    Guide camera: G3M2210M
    Filters: ToupTek Astro 1.25” HSO
    Total exposure: 7h
    NGC2237 Sample Image
    M16 Sample Image
    NGC6357
    Photographer: voice
    Telescope: Sky-Watcher
    Camera: ASI2600M
    Filters: ToupTek Astro 2” HSO
    Mount: UMi 17
    Integration: Hα: 36 × 600s ; SII: 36 × 600s ; OIII: 36 × 600s
    Total exposure: 18h
    NGC6357 Sample Image
    Installation
    • 36mm unframed filters: Special coating eliminates ghosting. To install, align the side with the inward-extending black ring toward the telescope for instant orientation and improved convenience.
    • 1.25" & 2" filters: Special coating removes front/back orientation concerns—simply screw in for fast, tool-free installation.
    HSO filters for astrophotography
    HSO filters for astrophotography
    HSO filters for astrophotography
    Warranty and Service
    • Quality Assurance Inspection: Each filter undergoes pre-delivery spectral testing and rigorous screening to guarantee consistent optical performance.
    • After-sales Policy: Includes a two-year warranty covering manufacturing defects, plus professional technical support and usage guidance.
    • For assistance, please contact our support team:
      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. Specifications are subject to change without notice. Please refer to the physical product for final details.

    Customer Reviews

    Based on 8 reviews
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    S
    Sonny Chart
    Unbeatable?

    Honestly im super impressed! at a price point of $500 for the entire set with a bandpass of 3.5/4nm is sceptical to say the least, there is/was concerns for halos or not working at fast (er) Focal ratios, or just generally not producing good results. HOWEVER! those concerns was very quicky gone! after unboxing and installing into the AFW (which was a little difficult to tell which way to go, but just follow the black rims) i was ready! finally a few nights came around and i got to test them. Easily producing my best SHO image ever! much better than my Baader CCD 6.5nm filters did! There is absolutely no halos in my testing, including on bright stars such as Sadr, Vega and Arcturus. And after 3 nights of imaging i got this stunning image of the North America Nebula. 12 hours worth of data, 4 hours per filter!

    If you are unsure what filters to go with, or want a cheap option that produces phenomenal results, these are the way to go! Very glad i picked these over anything else around this pricerange or even above! 5 stars from me, absolutely perfect

    User picture
    L
    Larry Cable
    now I know what way round to install them!

    Thanks Touptek for updating the installation guide ... very satisfied with the performance of all the filters in the EFW

    A+

    L
    Larry Cable
    great filters but...

    I would have given these a 5* review, however despite the description on the product page it was not entirely obvious which way round to install these in the EFW as both sides appeared to have the same tint and reflection, they really need some form of labelling to resolve this unambiguously

    Thank you very much for your suggestion. We have updated this information on the product detail page — please check.

    A
    Aditya Soni
    First Light With SHO filters

    Shot with SHO 36mm filters (3.5nm 4nm) using Touptek 26k mono paired with 6" F5 newt. Weather is not supportive so i couldn't make more images with this. But in coming months i am planning to test these filters with fast optics and see how it behave.

    User picture
    A
    Aditya Soni
    Initial Test: Impressive

    Although i am planning to make a detailed version of these filters, but weather is not on my side. So i could just manage few hours testing these new filters. I paired these SHO filters with Touptek 26k mono camera and fully customised 6" F5 newtonian. As a first light, i shot Rosette nebula and it came out really detailed. I didnt see any halo around bright star. I would test with some other fast optics and see how it performs. Overall, i am very satisfied.

    12

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