The Baader ASTF and ASSF solar filter foils are recommended for those seeking a no-compromise and extra-safe solution for solar observation.
The solar filter features Baader's highly popular and high-quality ND 5.0 foil, optimized for visual use. The filter's housing is made of metal and includes holes for "retaining pins," allowing it to be mounted on telescopes of various diameters. The package includes a set of self-adhesive Velcro, enabling quick and secure attachment of the solar filter foil to the front of the tube. For Newtonian telescopes and refractors, the filter can be secured both inside and outside the tube/dew shield, while for SC/MC telescopes, it is recommended to attach it only from the outside.
The ASTF series features a temperature-compensating housing that expands and contracts with the solar filter foil in response to temperature changes, ensuring the foil remains sufficiently "tight" to provide the best possible image quality.
The table below shows the sizing for Baader ASTF / ASSF filters. Pay attention to the outer diameter if mounting outside the tube, and the inner diameter if mounting inside.
| Model | Clear Aperture | Outer Diameter | Inner Diameter |
| ASSF 65 | 65 mm | 70 – 85 mm | 96 - 111 mm |
| ASTF 80 | 80 mm | 100 - 140 mm | 130 - 170 mm |
| ASSF 80 | 80 mm | 85 - 100 mm | 111 - 126 mm |
| ASTF 100 | 100 mm | 120 - 160 mm | 120 - 190 mm |
| ASSF 100 | 100 mm | 105 - 120 mm | 131 - 146 mm |
| ASSF 130 | 130 mm | 148 - 178 mm | 168 - 198 mm |
| ASTF 140 | 140 mm | 160 - 200 mm | 190 - 230 mm |
| ASSF 150 | 150 mm | 168 - 198 mm | 188 - 218 mm |
| ASTF 200 | 200 mm | 220 - 260 mm | 250 - 290 mm |
| ASTF 240 | 240 mm | 260 - 300 mm | 290 - 330 mm |