What is the principle of Budd membrane?

Budd membrane is actually a solar filter. It is a resin film plated with metal, which can be used for visual inspection and photography. It is very thin and its optical quality is very good. At present, there are two densities of available Budd film, which are 5.0 (visual) and 3.8 (photographic).

Astronomical telescopes must be equipped with Budd films or other filtering devices to observe the sun.

Otherwise, it will burn the fundus and instrument.

Budd membrane is a kind of solar filter. Different from other similar products, Budd film can reduce light and harmful radiation without reducing the contrast of the subject. In other words, using Budd film as a solar filter can get better image quality, and even record sunspot activity on the surface of the sun easily. The appearance of Budd film is silver film. Bader film, whose real name is AstroSolar, is produced by Bader Planetarium. Because the company transliterated as "Bader", this kind of solar observation film was called "Bader film" by astronomy enthusiasts, which means Bader film. As a product, Bader membrane only represents such a product, and its specifications are only divided into 3.8 and 5.0 according to density. 3.8 is mainly used for sunlight photography, and the corresponding light transmittance is about three ten thousandths. This kind of camera equipment is used for shooting, and its density is not enough to protect eyes from injury during visual inspection. One with a density of 5 and a corresponding light transmittance of1100000 is used as a solar filter for naked eye observation. If used for visual inspection, the density must be 5.0. Budd membrane-categories and uses

5.0 Bader film can effectively filter out the brightness of 40W incandescent bulbs. Through the film of 5.0, you can clearly see that the bright silk of this light bulb is like hair. 3.8 Budd film can not effectively filter out all the brightness of 40W incandescent bulbs. Through the film of 3.8, not only the filament of the bulb but also the outline of the bulb can be clearly seen. The membrane transmittance of 3.8 is 5.0 16 times, when the sun is normal brightness. 3.8 visual glare, can't see the details of the sun. 3.8 is suitable for taking photos, and 5 is suitable for visual inspection. However, it is ok to take photos with 5, but the exposure time is slightly longer. In addition, when shooting the total solar eclipse, Budd's film should be taken down early, otherwise it will miss the wonderful moment, a very short moment.

The traditional method is to use neutral gray filter when observing solar activity, solar eclipse and taking photos of the sun.