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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Baader Planetarium ASTF 80 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium Baader ASTF 100 AstroSolar® Telescope Filter (OD 5.1)
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 120 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 140 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 160 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 180 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 200 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 240 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 280 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 80 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium Baader ASTF 100 AstroSolar® Telescope Filter (OD 5.1)
Baader Planetarium ASTF 120 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 140 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 160 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 180 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 200 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 240 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite
Baader Planetarium ASTF 280 – AstroSolar® Telescope Filter OD 5.1 – ClearWhite

Baader Planetarium ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite

by Baader Planetarium
SKU BAA-2423010
$112.00 - $274.00
$112.00
$112.00 - $274.00
$112.00
Price Match Policy!
  • Available in nine sizes from 80mm to 280mm (ASTF 80 to ASTF 280) to suit your telescope
  • AstroSolar® Safety Film with Optical Density 5.1
  • Diffraction-limited optical quality for high-resolution views
  • Temperature-compensated filter cell keeps the film tension-free
  • Produces a neutral, ClearWhite image of the solar disk
  • Includes adjustable centering bolts and safety straps for secure attachment
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Qualifies for FREE Shipping in CONUS on orders over $350.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ASTF – AstroSolar® Telescope Filter OD 5.1 – ClearWhite

    The Baader ASTF AstroSolar® Telescope Filters deliver safe, diffraction-limited white-light solar viewing and are available in nine sizes, from the ASTF 80 for 80mm-class telescopes up to the ASTF 280 for 280mm (11-inch) instruments. Their renowned AstroSolar® film features an Optical Density of 5.1, safe for direct visual observation through the telescope and for solar photography, while rendering high-contrast, neutral white-light images of sunspots, granulation, faculae, and the partial phases of solar eclipses.

    AstroSolar OD 5.1 Film: Diffraction-Limited White-Light Views

    At the heart of every ASTF filter is Baader's AstroSolar® Safety Film, which achieves the optical quality of a high-precision, plane-parallel glass filter without the associated cost. It blocks harmful ultraviolet and infrared radiation, and unlike many lesser filters that produce an orange-tinted, low-contrast image, it delivers a "ClearWhite" view, showing the Sun in its natural color for objective analysis and photography.

    Temperature-Compensated Cell for Consistent Optical Integrity

    To maintain its diffraction-limited performance, AstroSolar® film must remain completely free of tension. Every ASTF filter features an advanced, temperature-compensating cell that allows the film to "float." The film is mounted on an injection-molded ring with the same thermal expansion properties, which is then held within the aluminum frame by a separate glass-fiber-reinforced ring. This design ensures the film never stretches or shrinks due to temperature changes, preserving its exquisite image quality from a frigid -30°C to a scorching +50°C.

    ASTF vs. DIY Filters: The Critical Role of a Tension-Free Mount

    Many homemade solar filters stretch the film taut like a drum skin in an attempt to make it look flat like glass. This process completely destroys the film's optical properties, resulting in blurry views unsuitable for high magnification. A correctly mounted AstroSolar® filter will exhibit slight waves; this is a sign that the film is tension-free and ready to perform as a precision optical window. The professional construction of the ASTF cell removes the guesswork and risk, guaranteeing optimal performance in every size.

    Secure and Adaptable Mounting System for Telescopes

    Each ASTF filter is equipped with a robust and versatile mounting system to ensure a safe, secure fit on your telescope's tube or dew shield. Adjustable centering bolts slide into the aluminum frame to center and clamp the filter on your instrument; the ASTF 120 and ASTF 200, for example, come with two sets of three 38mm-long bolts in 10mm and 20mm diameter, plus rubber plugs for unused openings. For added peace of mind, included safety straps with adhesive pads anchor the filter to your telescope, preventing it from being accidentally dislodged by wind or a sudden bump.

  • Why does the film in my ASTF filter look wrinkled?

    This is intentional and a sign of correct mounting. For the AstroSolar® film to deliver diffraction-limited images, it must be completely free from tension. The slight waves indicate the film is "floating" in its temperature-compensated cell, ready to perform like a high-precision optical window. A taut, perfectly flat film would produce a poor image.

    What is the difference between an ASTF filter and a simple glass solar filter?

    Baader ASTF filters use diffraction-limited AstroSolar® film, which acts as a precision optical window, providing much higher contrast and resolution than most affordable glass filters. The film also produces a neutral white image, whereas many glass filters add a strong orange or yellow color cast.

    How do I attach an ASTF filter securely to my telescope?

    Slide the adjustable centering bolts into the filter frame and position them so they grip the rim of your telescope tube or dew shield for a snug, centered fit. For maximum safety, you must also use the included safety straps, which create a secure connection between the filter cell and the telescope tube, preventing accidental removal by wind or a bump.

    Can I use the Baader ASTF filters for solar photography?

    Absolutely. The Optical Density 5.1 film is designed for both visual observing and high-resolution solar photography. Its high-contrast, neutral color image is ideal for capturing fine details like sunspot umbra and penumbra, faculae, surface granulation, and planetary transits with a DSLR or dedicated astronomy camera.

    Which ASTF size should I choose for my telescope?

    The ASTF range covers telescope classes from 80mm (ASTF 80) to 280mm (ASTF 280), e.g. small refractors, 8-inch Schmidt-Cassegrains and Dobsonians, and 11-inch SCTs. Because the filter clamps around the front of your instrument, always measure the outer diameter of your telescope tube front or dew shield before ordering to ensure a proper fit.

    Is an ASTF filter safe for viewing a total solar eclipse?

    ASTF filters are essential and perfectly safe for viewing all the partial phases of an eclipse. However, you MUST remove the filter from the telescope the moment totality begins to see the faint solar corona. As soon as the sun begins to reappear from behind the moon, the filter must be securely replaced immediately.

  • 80mm

    Aperture 80mm
    Optical Density (OD) 5.1
    Solar Image Color ClearWhite (Neutral White)
    Mounting Tension-free, temperature-compensating cell

    100mm

    Filter Type White-Light Solar Filter
    Aperture ~100mm Class Telescopes
    Film Baader AstroSolar® Safety Film
    Optical Density 5.1
    Image Color Neutral White
    Cell Construction Temperature-Compensated Aluminum Frame

    120mm

    Model ASTF 120
    Filter Type AstroSolar® Telescope Filter
    Optical Density OD 5.1
    Film Color ClearWhite
    Operating Temperature -30°C to +50°C
    Mounting System Adjustable Centering Bolts (10mm & 20mm)

    140mm

    Model ASTF 140
    Filter Type AstroSolar® Telescope Filter
    Optical Density 5.1
    Image Color ClearWhite (Neutral White)
    Mounting Cell Temperature-Compensated, Tension-Free
    Mounting System Adjustable centering bolts and safety straps

    160mm

    Model ASTF 160
    Filter Type AstroSolar® Telescope Filter
    Film Type AstroSolar® Safety Film
    Optical Density 5.1
    Image Color ClearWhite
    Mounting Cell Temperature-Compensating, Stress-Free
    Mounting System Adjustable centering bolts and safety straps

    180mm

    Model ASTF 180
    Aperture 180 mm
    Film Type AstroSolar® Safety Film
    Optical Density (OD) 5.1
    Image Color ClearWhite (Neutral)
    Mounting Cell Temperature-Compensated, Tension-Free

    200mm

    Model ASTF 200
    Aperture Telescopes up to 200mm
    Film Type AstroSolar® Safety Film
    Optical Density 5.1
    Image Color ClearWhite
    Operating Temperature -30°C to +50°C
    Mounting System 2 sets of adjustable centering pins (10mm & 20mm diameter, 38mm long)
    Safety Features 3x Safety straps with adhesive pads

    240mm

    Model ASTF 240
    Film Type AstroSolar® Safety Film
    Optical Density 5.1
    Image Color ClearWhite
    Mounting Cell Temperature-Compensated, Stress-Free
    Mounting System 2 sets of adjustable centering pins
    Safety Features 3x Safety straps with self-adhesive pads

    280mm

    Model ASTF 280
    Aperture 280mm
    Film Type AstroSolar® Safety Film
    Optical Density 5.1
    Image Color ClearWhite (Neutral)
    Mounting Cell Temperature-Compensating, Stress-Free
    Mounting System Adjustable centering bolts and safety straps
  • Baader Planetarium Warranty