ASTF: AstroSolar Telescope Filter OD 5.0 (80mm - 280mm)

ASTF – Baader Solar Filter for all high-end Telescopes (Refractors, Reflectors, CATs)

This family of solar filters is made in the most elaborate way. AstroSolar must not be put under stress, neither during mounting of 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 AstroSolar 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 breakage 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

• 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
• 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.
• Includes 3 Safety Straps with adhesive pads, screws, washers and instructions

NOTE: SCT Users must only mount the filter to the Outside of the Tube (the limited depth of the SCT front ID prevents adequate engagement of the centering bolts)

About BSF

After 15 years of offering AstroSolar film sheets as a 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. Many ready-made filters stretch the filter material like a drumhead in order to make it look like a piece of glass – this absolutely estroys 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 the traditional perception of quality, but AstroSolar must show slight ripples! When the film is put under stress by an improper cell mount its optical quality is degraded and it tehn performs just like a common coated glass-filter made of untreated floatglass.

With AstroSolar™ the Sun appears in it’ s real color – neutral white. Other films and most glass filters produce a blurry bluish, yellow-orange, or reddish Solar image, thereby cutting part of the spectrum. Especially with an orange sun, it is very hard to see faculae regions which are visible predominantly in the blue wing of the spectrum.

Baader Solar Filters are available in 3 types; ASTF - AstroSolar Telescope Filter, ASSF - AstroSolar Spotter Filter, and ASBF - AstroSolar Binocular Filter.  With a total 21 sizes, there is a Baader Solar Filter available to fit practically every Telescope, Spotting Scope and Binocular.

Supplied with each BSF

• Original Baader AstroSolar® Safety Film (OD 5.0), cell mounted and quality inspected by skilled members of Baader's 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
• 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 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 NOTE: SCT Users must only mount the filter to the Outside of the Tube (the limited depth of the SCT front ID prevents adequate engagement of the centering bolts)
• 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 screwdriver 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