| Full aperture glass filter for the Celestron C102 4" refractor telescope. Please note: Celestron has had a number of different lens shade sizes on their 4" aperture refractors over the years. Please measure the outer diameter of your lens shade before ordering. It must be 5.5" to use this filter. This full spectrum (white light) filter is made of high quality hand-selected glass, coated with Thousand Oaks exclusive Solar II Plus coatings. These metallic coatings are the most durable on the market. They consist of thin layers of vacuum-deposited nickel, chrome, and stainless steel. They reject 99.999% of the Sun’s spectrum of energy – from ultraviolet to infrared – protecting both your telescope optics and your eyesight. The glass filter element is mounted in a polished aluminum friction-fit cell that slips over the lens shade of the telescope. The filter cell is held snugly in place by felt strips on the inside of the cell lip. This filter is protected by the manufacturer’s unique 15-year warranty. The Sun appears yellow-orange through this filter, standing out briskly against a black sky. The filter can be used for both visual and photographic observations. This Thousand Oaks Type 2+ glass solar filter shows only sunspots and convection-cell granulation of the Sun’s surface. A higher cost hydrogen-alpha line band filter is needed to see flares, spicules, and solar prominences. Always remember to install the solar filter before pointing your telescope at the Sun to avoid instant and irreversible damage to your eyesight. Remove or cover the finderscope of your telescope as well, to avoid burning up its crosshair reticle, as well as to prevent accidental eyesight damage. Pinholes and minor surface scratches are common in vacuum-deposited metallic solar filter coatings. They do not let in enough extra light to cause a visual danger or scope-heating problem, and are no cause for alarm. All filters are tested by the manufacturer for safety before shipment. A “bright" pinhole may cause minor ghosting due to scattered light. If any ghosting is seen while observing, the pinhole(s) should be covered on the inside of the filter (the coated side) with a fine point black felt tip marker, small drop of paint, or a small dab of typewriter white-out. There is no optical danger if small pinholes or scratches are present, and the touch up procedure will not lessen the optical performance. The illustration shown is typical of a Thousand Oaks full aperture filter and is not necessarily an illustration of this specific filter.
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