We recommend Baader ASTF and ASSF mounted solar filter films for those seeking a no-compromise, exceptionally safe solution for solar observation.
The solar filter naturally features Baader's extremely popular, high-quality ND 5.0 film, optimised for visual use. The filter cell is made of metal and has holes that allow it to be fitted to telescopes of various diameters using "securing pins". The package includes a set of self-adhesive Velcro strips, allowing the solar filter film to be attached quickly and securely to the front of the tube. On Newtonian telescopes and refractors, the filter can be mounted externally or internally on the tube/dew shield; for SC/MC telescopes, external mounting only is recommended.
In the ASTF series, the filter is housed in a temperature-compensating cell that expands and contracts along with the solar filter film as temperatures change, ensuring that the film always remains sufficiently taut to provide the best possible image quality.
The table below shows the sizing of Baader ASTF / ASSF filters. Consider the outer diameter when mounting the filter externally on the tube, and the inner diameter when mounting it internally.
| Model | Clear aperture | Outer diameter | Inner diameter |
| ASSF 50 | 50 mm | 55 - 70 mm | 81 - 96 mm |
| 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 |