Baader 70mm AstroSolar Filter for Binoculars (order two), fits 75-90mm OD (ASBF-70)

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AstroSolar® filter material is mounted onto a plastic ring. The plastic ring itself works as stabilizing element for the filter cell. This ring is mounted onto the aluminum front frame. The thermal expansion coefficients of the plastic and the film are similar. This filter version is essentially similar to the ASSF in terms of mechanics. The only difference is that one side is cut off in order to make them usable on any binocular - even when the bridge is nearly closed. (depending on the binocular type).

    • Safe solar observation with all types of binoculars / safe solar photography with all camera lenses
    • AstroSolar® Safety Film OD 5.0, mounted stress free in high-quality cell
    • One side of filter cell shortened for use with binoculars.


  • Two filters are mandatory for binoculars, price is for one piece only
  • Original Baader AstroSolar® Safety Film (OD 5.0), cell-mounted and quality-inspected by skilled members of Baader Planetarium staff
  • Clear white IR-rejecting front ring with reinforced raised edges along the outer and inner circumference, designed to protect the solar filter material from contact with any sharp metal edge

  • Three (3) injection molded centering-bolts with threaded brass inserts to center the filter-cell in front of the tube opening. These bolts come in three different diameters, depending on the filter category (ASTF/ASSF/ASBF). Each bolt features injection molded rubber grip-faces, shaped to easily slide onto any telescope tube - but to remain firmly mounted.
  • No tool mounting and adjustment of the centering bolts to fit a wide variety of mechanical tube diameters. Bolts made to contact the outside or optional (if appropriate) the inside of the optical instrument tube. Refer to Clamping Range of Baader Solar Filters (inner/outer) for further details.
  • Non-rotating sliding fasteners made from aluminum that hold the centering bolts. These metal sliders are equipped with a machined indicator to point towards the adjustment index.
  • Additional Phillips screws are integrated into the sliding fasteners, so that the centering bolts can be firmly fastened with a screw driver if preferred by the user.

  • Index scale provided beside each adjustment slot - adjacent to each sliding fastener, for fast and repeatable adjustment of the filter cell onto different telescope tubes.
  • Black, sliding washers supplied to securely cover the full length of the adjustment slots in the aluminum frame - for blocking sunlight from passing through the filter cell beside the filter area.

  • Three (3) security straps included, to secure the position of the filter cell with Velcro-adhesive pads. A safety feature to absolutely ensure a secure fit in front of the telescope under any circumstances (ex. gust of wind).
  • Only for ASTF-filters: rubber plugs supplied as cover for closing unused adjustment slots in the aluminum frame.
  • Warning text printed onto the front side of each filter cell: Read the Instructions before use.
  • Cardboard gift box fit for safely shipping and storing the filter.

What's included:

  • ASBF Filter with 3 centering bolts (13mm diameter, 24mm length)
  • 3 Safety Straps with adhesive pads
  • Screws and washers
  • Instruction

Quick Reference for Astro-Physics Refractors, Binoculars and Finders.

  • Vario-Finder: ASBF-60
  • AP 10.5x70, 11x70, 15x70 & 16x70 Binoculars: ASBF-70

If you want to find a filter for a binocular, finder or camera not listed above, check this chart.

For more information, please refer to these documents :

Recommended Solar Filter Sizes – For Astro-Physics Refractors, Finder and Binoculars

Clamping Range of Baader Solar Filters


The New Baader Solar Filters (BSF), Astronomy Technology Today, March-April 2015

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