| A Celestron white light solar filter lets you watch the ever-changing face of the Sun in complete safety. You can see detail in sunspots, bright faculae near the limb of the Sun, limb darkening, and the mottled areas known as granules. It will not show solar flares or prominences (which requires a very expensive sub-Ångstrom H-alpha filter). A Celestron white light solar filter lets you extend your observing into the daytime, doubling the use you get from your telescope. Each filter is made of flexible Baader Astro Solar Safety Film, mounted in a durable molded cell. The cell either fits over the dewshield or into the front cell of your telescope. It is held in place by friction. Reflective metal coatings are vacuum-deposited on both sides of the Astro Solar film. These coatings have uniform density and good color balance across the entire field, providing razor-sharp images from edge to edge. The filter’s light transmission rating is ND-5. This means that the film transmits only 1/100,000th of the visible light while reflecting back (blocking) 99.999% of the unwanted light. The filter film itself absorbs all ultraviolet rays, while the dual metallic coatings reflect back towards the sky the infrared light, rendering both types of radiation absolutely harmless. The film is completely safe and durable (it won‘t break like a glass filter if you drop it). For added assurance, Baader Astro Solar film has been declared safe for direct solar viewing by the German National Bureau of Standards. A Celestron Astro Solar Film filter usually appears wrinkled on first inspection, but this has no effect on the optical performance. The best resolution is obtained when the filter is slightly relaxed or wrinkled. Because the film is so thin in relation to the wavelengths of visible light, light rays pass through the filter unaffected by any deviation from a flat filter surface due to the wrinkles. The Sun’s rays are through the filter so quickly that they simply don’t see the wrinkles. As a result, Astro Solar Safety Film is diffraction limited. The Celestron Astro Solar filter equals the optical performance of high quality glass filters at a fraction the cost. (Glass filters are much thicker in relation to the wavelength of light and must be carefully polished plane-parallel to avoid distorting the image). The Sun appears a neutral white through the filter, not blue or orange as it can appear in glass, Mylar, or polymer filters. The sky background is a dark grey. |
Printer friendly version
Email page link to a friend
