Used Baader 240mm AstroSolar ASTF Filter for 200-240mm O.D. Telescopes

  • Sale
  • $89.00
  • Regular price $159.00
  • Used Baader 240mm AstroSolar ASTF Filter for 200-240mm O.D. Telescopes

    • Sale
    • $89.00
    • Regular price $159.00
    • ITEM #



    • This is a used item in very good condition
    • Safely view the sun in white light

    Used Baader 240mm AstroSolar ASTF Filter for 200-240mm O.D. Telescopes

    Baader Solar Filters are designed to retain the real optical quality of the diffraction limited AstroSolar Safety Film in a precision mounted, temperature compensated cell. These professional quality Baader Solar Filters provide a secure and simple solution to observing and imaging the sun; utilizing AstroSolar Safety Film. Unlike most ready made filters- which stretch the filter material like a drumhead, destroying the image quality and rendering the film useless for any kind of high magnification work- AstroSolar works differently. By mounting the AstroSolar film in an entirely stress free fashion in a temperature compensated cell, it performs like a high precision planeoptical window. Don't let ripples in the film fool you. By not stretching the film tightly, it is permitted to act as it should without any image distortion. To acheive this highly controlled filter construction, the film is firmly adhered to an injection moulded ring. The substrate of that centering ring has the same thermal expansion rate as the Baader film. To complete the construction, this carrier ring is free floating within an aluminum frame, held in place with an additional holding ring made of fiber reinforced plastic. This holding ring's job is to keep your filter safe from breakage. Baader SolarFilter ASTF filters are highly temperature stable, operating perfectly in temperatures between -22F and 122F, nearly any observing conditions you might find yourself in.

    Often H-Alpha filters, which produce an image in a yellow-orange tone, are refered to as a "natural" colored image because we perceive the sun to be yellow and orange. In truth, Baader solar film produced a natural color view of the Sun - pure, white light with a slight blue tint. This permits visibility of the faculae regions of the Sun which are best seen in the blue portion of the visual spectrum. And because the Baader ASTF filters have total neutral color balance you can use a variety of color filters on the eyepiece to bring out further detail on the solar surface. The addition of a Baader Solar Continuum filter will further improve already excellent image stability and clarity. Faculae or bright spots on the sun are further enhanced with the use of a Continuum filter as well.

    The end result is a white-light solar filter that exhibits no astigmatism during cold weather observing or on hot summer days, and is highly suitable for high magnification and detailed sun spot study.


    • Skillfully constructed and assembled by Baader staff.
    • Holding ring with raised edges helps to keep sharp edges away from the film.
    • 3 centering bolts with threaded brass inserts to center the film to the center of your telescope optical tube. Moulded rubber grips slide onto the telescope easily but provide a firm grip.
    • Tool-free mounting and adjustment. The centering bolts are made to make contact with the outside or inside of the telescope optical tube. Inside mounting required a clear depth of at least 20mm on the inner ring of the optical tube.
    • Aluminum sliding fasteners are non-rotating and have Phillips head screws so that they can be firmly tightened to the telescope. This prevents slight shifts in filter position and serves as an additional safety feature ensuring your filter stays in place at all times.
    • A handy scale is next to each adjustment bolt for quick repeated adjustment with each use.
    • Black sliding washers supplied to securely cover the full length of the adjustment slots in the aluminum frame for blocking sunlight from passing trough the filter cell beside the filter area.
    • Three 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 circumstance.
    • Carefully packaged in a stiff cardboard box with special insert to keep your filter in tightly in place while shipping and transporting.
    • Alpine # Baader #



      Ideally Suited forAperture

      Range (mm)

      Clamping Range

      Inner Tube Dia

      Clamping Range

      Outer Tube Dia

      ASTF-80 24593310 80 / 3.2 70 - 90 130 - 170 100 - 140
      ASTF-100 24593311 100 / 3.9 90 - 110 150 - 190 120 - 160
      ASTF-120 24593312 120 / 4.7 110 - 130 170 - 210 140 - 180
      ASTF-140 24593313 140 / 3.2 130 - 150 190 - 230 160 - 200
      ASTF-160 24593314 160 / 5.5 150 - 170 210 - 250 180 - 220
      ASTF-180 24593315 180 / 7.1 170 - 190 230 - 270 200 - 240
      ASTF-200 24593316 200 / 7.9 190 - 210 250 - 290 220 - 260
      ASTF-240 24593317 240 / 9.5 230 - 250 290 - 330 260 - 300
      ASTF-280 24593318 280 / 11.0 270 - 290 330 - 370 300 - 340

        Additional Information

        ConditionVery good
        Warranty90 Day
    • Baader ASTF 240 solar filter
    • Mounting hardware
    • Original box

    Questions & Answers

    Ask a Question
    • Hi! It works in 8"SCT Celestron OTA? Regards!!!

      After reviewing the bullet points of additional information, this Solar Film is suited for Apertures less than 8". I would recommend the next size up.

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