However, front-mounted filters, especially glass and Mylar filters, can slightly reduce the contrast and sharpness of the solar image. They have the advantage of keeping the optics of the telescope cool, which can help with obtaining steady images, and they can be used with reflectors, compound telescopes, and refractors. Solar filters made of mounted glass, Mylar, and AstroSolar film are all examples of front-mounted solar filters than block 99.999% of the Sun's light from entering a telescope tube. You can use your regular eyepieces with your telescope to observe the Sun with these front-mounted solar filters. These filters, once safely mounted, are all you need to safely observe the Sun with a telescope. White-light solar filters come in three main varieties: glass filters, mylar filters, and the specialized AstroSolar film manufactured by Baader.
White-light solar filters are usually mounted in mechanical cells or holders that fit over the objectives of most types of telescopes, including refractors, Newtonian reflectors, and Schmidt-Cassegrain and Maksutov-Cassegrain reflectors with a wide range of apertures, from 2" to 14" or more. The most economical way to view the Sun directly with a telescope involves mounting a white-light filter in front of the objective lens or mirror to reduce the intensity of the visible, infrared, and ultraviolet light entering your telescope to a level of intensity that's safe for your eyes and your telescope. But if you want to see the fascinating features on in the Sun's photosphere like sunspots or granulation or solar flares, you will need the resolution and magnification of a telescope. As explained in the second article in this series, observing the Sun with just your eyes and safe eclipse glasses or #14 welder's glass is good enough for seeing large sunspot groups or solar eclipses.