Solar filters for observing the Sun
More experienced sun watchers prefer specially designed sunscreens that reduce the sun’s energy to harmless levels. Filters fall into two main categories: First, white light filters. These block 99.999% of sunlight to allow us to see the Sun’s visible surface, or photosphere, revealing magnificent views of ever-changing sunspots. Then come the Hydrogen-alpha (Hα) filters. These block all wavelengths of sunlight except one – the wavelength emitted by hot hydrogen atoms. Hα filters reveal details about the Sun that are invisible using white light filters, including flame-like prominences and intricate glowing threads called solar beaches, which are usually found near sunspots.
White light filters
Known as “aperture filters”, white light filters fit the front of a telescope to reduce solar energy to a safe level before it enters the optical system , including your eyes. They are usually made from glass or a polymeric material, such as Mylar, and fit securely in a telescope or binoculars (although you need two filters for these, one per barrel).
White light filters should only be purchased from a reputable source. Some of the most popular include Astrozap (astrozap.com), Baader Planetarium (astrosolar.com/en), Celestron (celestron.com), Explore Scientific (explorescientificusa.com), Kendrick Astro Instruments (kendrickastro.com), Meade Instruments (www. .meade.com), Orion Telescopes (www.telescope.com) and Thousand Oaks Optical (thousandoaksoptical.com).