This is an off-axis solar filter with clear aperture of 101mm or 4.00 inches. For telescopes up to 5 inches aperture, off-axis is not an advantage. Larger apertures suffer more from daytime atmospheric turbulence. This turbulence is magnified by the aperture. Perfect daytime "seeing" only occurs about 1 percent of the time. Off-axis reduces the aperture and increases the focal ratio thus reducing the turbulent effects. For average use we recommend off-axis for 10-inch and larger telescopes. The solar image is not darker with reduced aperture as we allow for this in the coating density. When viewing through the eyepiece, the field of view is not reduced; it looks the same as full aperture. If full aperture is still preferred, it can be stopped down using a simple mask as conditions dictate.
The inside diameter of this filter is 305mm or 12.00 inches. This is suitable for the Meade 10-inch LX200 and LXD-75 and other telescopes. Please check the outside diameter of your telescope tube before ordering; the filter must be a snug fit or it may fall off.
Made with high quality hand select glass coated with our exclusive Solar II Plus. The most durable glass filter on the market. Transmission is 1/1,000th of 1 percent (Optical Density 5). Great for both visual and photographic use. Solar image is yellow-orange. Guaranteed fifteen years.
This filter is completely safe for unlimited visual use. If handled with care and common sense, it will last a minimum of 20 years to life.
All the heat and intense light is blocked before it can enter the telescope. Your telescope may get warm from sunlight shining on it, not from the small amount of visible light transmitted through the filter.
Sunspots and surface granulation are the two main features. The only detail that cannot be seen with a standard filter (commonly called white light filter) are prominence and flares which require our highly specialized H-Alpha filter system.