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  • ANTLIA ULTRA 2.8nm SII Ultra Narrowband Filter - 36mm Unmounted

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    Antlia ULTRA SII 2.8nm QUARTZ Ultra-Narrowband Filter - 36mm Unmounted (glass only)

    Now with a 2.8nm bandwidth! 

    Antlia 2.8nm H-a, SII and OIII Ultra Filter - Extra Narrowband filters - 36mm unmounted

    The Antlia SHO 2.8nm Ultra series filters are made with   quartz glass and undergo precisely controlled coating processes to ensure optimal performance. The 2.8nm Ultra series is designed with a FWHM (full width half maximum) of 2.8nm +0.5/-0.1nm and a transmission efficiency >95-97% at the Central Wavelength.

    The quartz glass possesses an ultra-low thermal expansion coefficient with outstanding thermal and mechanical properties. When combined with advanced coating processes, these filters exhibit remarkable durability for imaging and research in the most challenging environmental conditions.

    Compared to the 3nm Pro series, the 2.8nm Ultra series coated on quartz glass exhibits higher transmittance with Ha/SII97% and OIII95%. These filters are estimated to improve signal by 20-30% in your images. Additionally, the Ultra series narrowband filter boasts a narrower FWHM of 2.8nm+0.5/-0.1nm, resulting in an exceptionally high Signal to Noise Ratio for deep sky photography.

    Technical Specifications:

     

    Hydrogen-alpha

    Sulfur-II

    Oxygen III

    FWHM

    2.8nm +0.5/-0.1nm

    2.8nm +0.5/-0.1nm

    2.8nm +0.5/-0.1nm

    CWL (Central Wavelength)

    656.3nm

    672.4nm

    500.7nm

    Peak Transmission

    97%

    97%

    95%

    Blocking

    ≥OD5

    Filter Thickness

    2mm+/-0.05mm

     

    Sizes:

    currently available size is only 36mm unmounted (glass only)

    The main features and application:

    - High transmittance (Ha/SII≥97%,OIII≥95%)and the narrow FWHM 2.8nm +0.5/-0.1nm to maximize contrast;

    - Flat-top spectrum minimizes the loss in transmission due to the Center Wavelength (CWL)-shift;

    - Out of band blocking specification is designed to OD5 (0.001%) to block interference from other wavelengths and minimize halos around bright stars;

    - Made of quartz glass, excellent durability and thermal stability, better fracture resistance and scratch resistance, improved coating resilience to cleaning;

    - Filters are resistant to scratches;

    - Identical filter thickness to existing standards and double-sided fine polishing , with utmost care for parfocality

    - The SHO 2.8nm Ultra filters are recommended for use in optics with a Focus Ratio of ≥ f/3.5 for best optical performance;

    - 100% of production are scanned individually, all transmission and blocking (OD) data in the box are actual, measured spectra and transmission;

    - All Antlia filters are coated to the edge of the substrate and unmounted narrowband filters are edge blackened to eliminate internal reflections from stray light;

    - Warranty: 3-years against delamination.

    Not Recommended:

    • Solar Observing and imaging
    • Visual observation

    IMPORTANT! DO NOT LOOK AT THE SUN WITH ANTLIA FILTERS.
    Serious eye damage will result if you fail to observe the warning.

    USER CONTRIBUTION:

    As authorised dealers for all our products they come with a full manufacturers warranty along with our satisfaction guaranteed, no-questions-asked full refund policy for a full 30 days.

    Please see our returns policy for full details.

    We ship direct from UK warehouses and provide free shipping on all purchases within England, Scotland and Wales (Excluding highlands and Islands)

    We use UPS, DHL, DHL Express, Parcelforce or Royal Mail for all orders.

    Estimated delivery time is displayed at checkout.

    See our shipping policy for more details.

    Should you be outside the free shipping area then please contact us to discuss shipping options as prices vary depending on products and delivery location.

    Got questions? Read through our FAQ list to see if it's answered there! If not, please contact us via this form.

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