There are two types of solar observing filters: white light and hydrogen-alpha. White light solar filters are simply very dark neutral density filters. These allow you to see sunspots on the surface of the sun and are ideal for viewing solar eclipses and transits of Mercury or Venus. Hydrogen-alpha filters are narrowband filters. These allow you to view solar flares, prominences, and other associated activity.
Unlike other types of filters for astronomical observing, solar filters fit over the front of the telescope, completely covering the aperture. This is to protect not only the observer’s eyes but also the optics themselves. The telescope’s optics would become very rapidly heated and potentially damaged without the filter in place.
If you’re interested in viewing solar prominences, solar flares, solar corona, and other unusual details using your existing telescope, then a Solar Hydrogen-Alpha (H-alpha) Filter is a perfect choice. These high quality filters are designed for blocking all light except for the h-alpha wave length. This is an important emission line for solar observation, as the Sun’s surface layer contains a high proportion of hydrogen. The H-alpha filter allows safe observation of the entire solar disc, providing superb views of prominences, chromosphere, and surface details such as sunspots, plagues, flares, filaments, and granulation. They are meant for both visual observing and astrophotography.
We offer white light solar filters crafted from Baader AstroSolar film and specially coated glass. This material is surrounded by a sturdy material like aluminum, and the whole thing slips over the end of your telescope tube. Once the filter is in place, it blocks out the harmful rays emitted by the Sun and lets safe wavelengths through, allowing you to observe or photograph sunspots on the surface of the Sun. The filter also lets you experience solar eclipses or planetary transits safely. It is important to choose a solar filter that fits snugly, so before buying your filter, you should measure the outside diameter of your telescope carefully. Once you have this measurement, it is a simple matter to find the proper filter based on size.