Black Polymer Solar Filters
Description
View sunspots and granulation of the surface of the Sun, while protecting both your telescope optics and your eyes with Thousand Oaks full spectrum (white light) SOLAR Filters.
BLACK POLYMER: A lower cost alternative where lower magnification is used such as with binoculars, finder scopes and small telescopes. Stronger than “Mylar” with the filtering properties protected within the substrate. Solar image is yellow-orange. Also available in sheets. Guaranteed 10 years.
Each filter (whether glass or film) is mounted in a polished friction-fit aluminum cell with a lip that slips over the objective end of the telescope. This prevents the Sun°۪s heat from building up inside the telescope and possibly damaging the components inside. The filter cell is held snugly in place by 1/32° thick felt strips glued to the inside of the cell lip.
The filters below list the inside diameter (I.D.) of their cell°۪s lip. They are designed to fit telescopes with an outer diameter no larger than 1/16° smaller than the cell size. (The 1/16° difference is the total thickness of the felt holding the filter cell in place.) If you do not see your brand of telescope and model listed, simply choose the closest filter cell I.D. size that is larger than the outside diameter measurement of your telescope. For example, a 4.25° I.D. filter would fit telescope diameters from 4° to 4–3/16°. Do not choose an I.D. size the same as your telescope outer diameter, since it will be too tight and will not allow room for the felt lining. Ample extra self-adhesive felt is included so you can double or triple the layers of felt for a custom fit.
The polymer filters have a 15-year manufacturer’s warranty against flaws in materials and workmanship. If handled with care and common sense, all types can last 20 years to life.
The Sun appears yellow-orange through a Thousand Oaks filter, standing out briskly against a black sky. The filter can be used for both visual and photographic observation, using a camera ISO setting of 100 or higher. Thousand Oaks white light solar filters show only sunspots and convection-cell granulation of the Sun’s surface. A much higher cost hydrogen-alpha line band filter is needed to see flares, spicules, and solar prominences.
Full aperture solar filters use a filter element with a diameter close to or equal to that of the aperture of your telescope itself. The resolution of the filtered image is thereby equal to that of your telescope, showing the most amount of solar detail.
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 finder-scope 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 this 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, a 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 illustrations shown below are typical of Thousand Oaks filters and do not necessarily show the specific filters described.