Alpine Astronomical 140mm Baader AstroSolar BDSF 3.8 White-Light Digital Solar Filter for Telescopes

Alpine Astronomical 140mm Baader AstroSolar BDSF 3.8 White-Light Digital Solar Filter for Telescopes

Alpine Astronomical 140mm Baader AstroSolar BDSF 3.8 White-Light Digital Solar Filter for Telescopes

B&H # ALBDSF140 MFR # BDSF-140
Special Order
Expected availability: 7-14 business days

Product Highlights

  • For Digital Imaging with Nighttime OTAs
  • For Detailed, High-Magnification Viewing
  • Broad-Band Neutral-White Color
  • Optical Density of 3.8
  • 130-150mm Recommended Aperture
  • Front Clear White IR-Rejecting Ring
  • Three Centering Bolts and Safety Straps
  • No Tools or Modifications Required
  • Not Safe for Direct Solar Viewing
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SAFETY FIRST: Observing the Sun without the proper protection may result in serious personal injury, including permanent eye damage and blindness, and/or damage to equipment. Never point an optic at the sun without an approved solar filter on the front of the optic. For direct solar viewing, viewing the sun through an optic, or when using cameras with an optical viewfinder, ensure your filter is ISO 12312-2 (also written as ISO 12312-2:2015) certified. Never use photographic neutral density filters for direct solar viewing, viewing the sun through an optic, or when using cameras with an optical viewfinder.

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Alpine Astronomical BDSF-140 overview

  • 1Description

Unlike many white-light solar filters that produce views of the sun with a red-orange, bluish, or yellow tint, the Alpine Astronomical 140mm Baader AstroSolar BDSF 3.8 White-Light Digital Solar Filter reveals the sun in its natural white color. With an optical density of 3.8, this iteration is specifically designed for digital imaging of the sun and all phases of a solar eclipse through an optic like a telescope or extreme telephoto lenses — showing more surface details with greater clarity versus other types of solar filters. The filter is mounted onto a clear-white IR-rejecting plastic ring, which acts as stabilizing element for the filter cell, and the ring is in turn mounted onto the aluminum front frame. The thermal expansion coefficient of the plastic and the film are similar to minimize thermal stress on the film for increased resistance to developing pinholes or tears.

With the ability to be installed on the outside or inside of an optical tube assembly, dew shield, or corrector plate retaining ring, this filter provides a safe way to view the sun through conventional nighttime telescopes. Recommended for apertures from 130-150mm, the filter is engineered with three centering bolts that can fit OTAs, dew shields or corrector plates with an outside diameter of 160-200mm, or an inside diameter of 190-230mm. Due to the shallow depth of the corrector plate on most catadioptric OTAs, for secure and safe use Alpine Astronomical only recommends outside mounting on Cassegrain-style telescopes.

This filter is only intended for digital imaging of the sun, and is not safe for direct solar viewing or for use on cameras with an optical viewfinder. Only use on cameras with an electronic viewfinder (EVF) or Live-View option. If you do not know what kind of viewfinder your camera has, do not use this filter.

  • For the correct fit, measure the outside or inside diameter of the dew shield/lens housing - including hardware like retaining rings and screw heads — and choose the size that matches the measurement with some extra room
  • When used on Schmidt-Cassegrain, Maksutov-Cassegrain, or other catadioptric OTAs, outside mounting is required as the limited depth of the front inside diameter prevents full and secure engagement of the centering bolts
  • Recommended for 130-150mm apertures
  • 190-230mm inside diameters
  • 160-200mm outside diameter
In the Box
Alpine Astronomical 140mm Baader AstroSolar BDSF 3.8 White-Light Digital Solar Filter for Telescopes
  • 3 x Screws
  • 3 x Washers
  • 3 x Centering Bolts
  • 3 x Rubber Plugs
  • 3 x Safety Straps with Adhesive Pads
  • Limited 2-Year Warranty
  • Table of Contents
    • 1Description

    Alpine Astronomical BDSF-140 specs

    Bandpass White-light, broadband
    Clear Aperture 140mm
    Diameter 230mm
    Weight 6.1 oz / 173.0 g
    Packaging Info
    Package Weight 0.85 lb
    Box Dimensions (LxWxH) 10.9 x 10.7 x 1.4"

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