Baader AstroSolar Safety Film 140x155mm ND 5.0 - visual solar filter foil
Want to observe the Sun through a telescope without risking your eyesight or damaging your optics? Baader AstroSolar Safety Film is the globally recognised standard among amateur and professional astronomers for making objective solar filters. This 140x155mm sheet lets you easily and affordably build a custom filter perfectly sized for your telescope - with results that rival or exceed many commercially sold filters at significantly higher prices.
Optical density and safety
The film has an optical density of ND 5.0, which means it transmits only 0.00001 of incoming light - just 0.001%. This is precisely the value recommended for safe visual solar observation. The filter effectively blocks not only visible light but also hazardous UV and IR radiation. At only 12 micrometres thick, the film is extremely lightweight and easy to work with. Minor creases or slight waviness in the material have virtually no negative effect on image quality - a significant advantage over glass filters, which must be perfectly flat.
Image quality
Optically, AstroSolar film will impress even experienced observers. It delivers a bright, high-contrast, sharp image even at high magnifications. The solar disk is rendered in natural white light, allowing sunspots, granulation and faculae to stand out with maximum clarity. The 140x155mm size is designed to cover telescope objectives up to 130mm in diameter, making it compatible with the vast majority of refractors, reflectors and compact apochromatic telescopes used by beginners and intermediate astronomers alike.
How to make your own solar filter
Building an objective filter is straightforward:
- Carefully place the film into a paper or cardboard frame sized to fit your telescope tube.
- Make sure the film has no cracks or holes - inspect it against a light source before each use.
- Never use a filter that is perforated or torn.
- With proper care, filters made from AstroSolar film will last for many years.
The whole project can be completed in an afternoon, and the result is fully comparable to commercial filters.
Visual vs. photographic version - which one to choose?
Baader AstroSolar film is available in two versions - visual (ND 5.0) and photographic (ND 3.8). The visual version is intended exclusively for observation with the naked eye or with a camera using very short exposures, where maximum light reduction is required. The ND 5.0 film is the only correct choice for direct visual solar observation through a telescope - the photographic ND 3.8 version transmits more light and would be dangerous for the eye. If you plan solar photography with shorter exposure times or low-sensitivity sensors, the photographic version may be appropriate. For any visual use, always choose ND 5.0.
Product specifications
| Parameter |
Value |
| Film size |
140 x 155 mm |
| Optical density |
ND 5.0 |
| Light transmission |
0.001% (0.00001) |
| Film thickness |
12 micrometres |
| Maximum objective diameter |
up to 130 mm |
| Intended use |
Visual solar observation |
| UV/IR blocking |
Yes |
| Manufacturer |
Baader Planetarium, Germany |
About Baader Planetarium
Baader Planetarium is a German manufacturer with decades of experience in astronomical optics and accessories. Baader AstroSolar film meets strict safety standards and is used by professional observatories as well as thousands of dedicated astronomers around the world. It is a trusted investment in safety, image quality and the pleasure of solar observation - and at this price point, there is simply no better alternative on the market.
