Baader Solar Filters provide a professional & secure solution to observe & image the Sun using Astro Solar Safety Film. Many ready-made filters stretch the filter material like a drumhead in order to make it look like a piece of glass Â- this absolutely destroys the image quality, rendering the film useless for high magnification work. Astro Solar film must be mounted entirely un-stressed in order to perform like a high precision planeoptical window. It sounds like a contradiction with traditional perception of quality, but Astro Solar must show slight ripples!