Baader 200mm AstroSolar ASTF Filter, fits 220-260mm OD (ASTF-200)

Brand :

SOLD OUT, until later in 2024

The current solar maximum cycle will continue to peak throughout 2024 and beyond offering sunspots that will change and morph from one day to the next. Many people viewed the sun for the first time during the April 8th eclipse and were wowed by the level of activity. We encourage you to continue popping your scope out during the day to observe or photograph the progression of sunspots across the surface of our dynamic sun.

The ASTF family of solar filters is constructed in a more elaborate manner than either the ASSF or ASBF and should be considered if you will be observing in extreme temperatures. 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 firmly cemented onto an injection molded ring, whereas the substrate of that ring has the same thermal expansion as 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 degrees C or +50 degrees C.

  • 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 a temperature compensated cell.
  • Suitable for highest magnifications and detailed observation of individual sunspots.
  • No astigmatism during winter observation or with temperature changes in summer.
  • 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 needed for 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:

ASTF Filter (with apertures from 80 to 280mm):

  • Two sets of centering bolts in 38mm length; 3 bolts with 10mm diameter and 3 bolts with 20mm diameter
  • Adjustable to the outside tube diameter of your telescope lens or dew shield.
  • Three safety straps with glue-pads
  • Three rubber plugs to cover the unused holes.

Quick Reference for Astro-Physics Refractors, Binoculars and Finders

  • Vario-Finder and some binoculars: ASBF-60
  • 90 & 92mm Stowaway dew shield (past and current): ASSF-100, ASBF-100 (flat side may prevent interference if you are mounting on top of another scope)
  • Traveler dew shield: ASTF-100
  • 130GT & 130GTX dew shield: ASSF-130
  • 130EDFS, 130EDT & Star130ED dew shield: ASSF-130
  • 140EDF27 & 140EDF4 dew shield: ASSF-150, ASTF-140
  • 155EDF, 155EDFS, 155EDT, Star155ED dew shield: ASSF-150, ASTF-160
  • 155EDF, 155EDFS, 155EDT, Star155ED Lens Cell: ASSF-150
  • 160EDF dew shield: ASSF-150, ASTF-160
  • 175EDF dew shield: ASTF-180
  • 180EDF lens cell: ASTF:160
  • 180EDF dew shield: ASTF-180
  • 206EDF dew shield or lens cell: ASTF-200

For additional options or if you want to find a filter for a scope 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

Measuring your Telescope, Binocular, Finder or Camera

To ensure proper fit of the solar filter, you must measure the outside diameter of the dew shield or lens cell of your telescope or outside diameter of the binocular or camera lens. 
Metric conversion: 25.4mm = 1 inch. 


All solar filter sales are final. Please measure carefully before you place your order so that you order the correct size. Also, pay attention to the diameter of the filter material itself so that you select the filter that you want. For instance, it is possible to order a filter for a Traveler with only an 80mm diameter of AstroSolar® filter material. However you will likely prefer a filter with 100mm diameter of the actual filter material. Review all of the specifications carefully.