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Please note that the shown ASTF Filter is an example image of ASTF 160 filter. Inner radius variies on other ASTF-Filters

ASTF – Baader Solar Filter for high-end telescopes

Includes 19% VAT
5 out of 5 based on 2 customer ratings
(2 customer reviews)
Delivery Time: approx. 2-3 workdays
  • Safe for solar observation and photography with all high-end telescopes and extreme tele-lenses
  • AstroSolar Safety Film OD 5.0, mounted stress free in temperature compensated cell
  • suitable for highest magnifications and detailed observation of individual sunspots
  • no astigmatism during winter observation or with temperature changes in summer

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Product Description

(…) I am extremely pleased with the performance of the ASTF. It exceeded my expectations and provided a white light solar view that was brighter and more detailed than the standard full aperture glass filter I have could provide. The primary and secondary mechanisms to secure the ASTF to the dew shield were both robust and provided completely safe operation, even in windy conditions. Best of all though was the performance, clearly besting my glass filter! Finally, all components of the product were very nicely engineered and showed a high level of quality and construction. An excellent product in performance, engineering, and construction, and now a permanent part of my equipment for white light solar observing! © William Paolini. Read the full review:


Review ASTF White Light Filter - William Paolini

Download baader-astf-whitelight-filter.pdf

After 15 years of offering AstroSolar® film sheets as DIY-product, this system of Baader Solar Filters™ is designed to retain the true optical quality of the diffraction limited AstroSolar® Safety Film.

Baader Solar Filters™ provide a professional and secure solution to observe and image the Sun using AstroSolar® Safety Film OD 5.0. Many ready made filters do stretch the filter material like a drumhead in order to make it look like a piece of glass – this absolutely does destroy the image quality, rendering the film useless for high magnification work. AstroSolar® must be mounted entirely stress free in order to perform like a high precision planeoptical window. It sounds like a contradiction with traditional perception of quality, but AstroSolar® must show slight ripples! Only when the film is being put under stress by an improper cell mount it performs just like any single side coated glass-filter made of untreated floatglass.

ASTF – Baader Solar Filter for high-end Telescopes

This family of solar filters is made in the most elaborate way. AstroSolar® must not be put under stress, neither during mounting the film, nor during any temperature change. For this reason the ASTF-Filter features a temperature compensated cell. The film itself is repeatably cemented onto an injection molded ring, whereas the substrate of that ring has the same thermal expansion like the Astro Solar Filter material itself. This free floating film-carrier ring is held onto the aluminum frame with the help of another holding ring made of fiber reinforced plastic – for a maximum of security against breaking of the cell. This temperature compensated cell enables the AstroSolar® filter material to retain its excellent optical quality at any temperature – be it -30°C or +50°C.


Scope of supply: ASTF Filter with apertures from 80 to 180mm (200 – 280mm not yet available) come with two sets of centering bolts in 38mm length. 3 bolts with 10mm diameter and 3 bolts with 20mm diameter, adjustable to the tube diameter of your telescope or dew cap. In addition three safety straps with glue-pads and three rubber plugs to cover the holes that are not used.

All Baader Solar Filters feature:

  • original Baader AstroSolar® Safety Film (OD 5.0), cell mounted and quality inspected by skilled members of our staff
  • clear white IR-rejecting front ring with reinforcing raised edges along the outer and inner circumference, designed to protect the solar filter material from contact with any sharp metal edge
  • 2 sets of 3 injection molded centering-bolts (length 38mm) with threaded brass inserts to center the filter-cell in front of the tube opening. These bolts come in two diameters, 10mm and 20mm. Each bolt features injection molded rubber grip-faces, shaped to easily slide onto any telescope tube – but to come off very hard
  • 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
  • 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 trough the filter cell beside the filter area
  • only for ASTF-filters: rubber plugs supplied as cover for closing unused adjustment slots in the aluminum frame
  • 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 circumstances (gust of wind asf)
  • warning text printed onto the front side of each filter cell: Read the Instructions before use
  • cardboard gift box fit for safely shipping the filter

More Information on AstroSolar® Safety Film:

Additional Information


80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 240 mm, 280 mm

Optical Density

OD 5.0

Solar Film

AstroSolar Safety Film


Solar Photography, Visual Observation, Whitelight

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5 out of 5 stars

2 reviews

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What others are saying

  1. Dan Cottle

    5 out of 5 Excellent - used to successfully observe the Transit of Mercury May 2016

    (verified owner)

    This is a useful filter for observing the Sun. It requires very little assembly and is a secure fit over our Meade LX90 10 inch telescope with the provided velcro fastenings. As with other solar filters nothing is visible unless the telescope is pointed directly at the Sun – it is too dark for any other purpose. It does make it very easy to see sunspots, some surface detail and our primary use which was the transit of Mercury.
    Very satisfied.

    IMG_0002 small

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  2. Marcel Fontaine

    5 out of 5 Very satisfied of the filter - but also of Baader's pre-delivery cooperation

    I have purchased this Astrosolar filter to observe the transit of Mercury, and it was a very positive experience. The filter was easy to assemble, it fit very securely on my refractor (a Takahashi 128) and the observation was excellent : a sharp image of the Sun, very comfortable for the eyes, a detailed view of a large sunspot and the magnificent transit of the tiny black circle of the little planet.
    I am looking forward to observing the Sun regularly (Belgian clouds permitting !) with this valuable new addition to my equipment.
    But I also want to thank Baader-Planetarium for their very positive cooperation following my order.
    I had asked if they could assure me that the filter would be delivered in time for the Mercury transit (even a few days before to let me assemble the filter and get used to it); the answer was affirmative if I could order and pay right away. This I tried to do. My order went through with no problem, but to my surprise, Paypal refused my payment with my usual credit card ! I tried again and again, struggling in vain to understand the reason, but it was hopeless and there was no way to get a direct explanation from Paypal. I told Baader about this problem and that spontaneously told me that due to the little time left before the transit, they would still send me the filter right away and ask me to pay the invoice by bank transfer, after delivery. Two days later, from Germany to Belgium, I had received the filter, which I paid by bank transfer (the explanation of my credit card problem came later). I am very thankful for this, especially as I was a first-time customer.

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