instructions:
mounting:
The inside of the cell will be lined with felt or unlined depending on the telescope brand and aperture. If your filter is too loose, it can be custom fitted using felt or tape on inside of cell. The filter should not fit too tightly or the optical surface may be distorted due to stress on the cell. If you have purchased an un-mounted filter and will be mounting it in your own cell, be sure to mount it in such a way as to allow for thermal expansion and contraction. The glass should not be firmly cemented or clamped within the cell or holder.
Please note each filter will be shipped with strips of Velcro, which should be used to secure the filter to the telescope for added safety
If you do not have a solar filter for your finder-scope, keep it covered. Looking through the finder-scope at the sun without a proper filter can damage your eye in a fraction of a second. With a little practice you can obtain a close alignment by moving your tube assembly until the smallest shadow of the tube assembly is cast behind you.
Solar Filter Cleaning Instructions:
Glass Solar Filters: Clean only with Isopropyl (rubbing) alcohol and a soft tissue. Apply generous amounts of alcohol to the tissue and rub lightly across the surface using long stokes. Lightly wipe dry with fresh tissue. Since the coating is on the backside of the glass facing the telescope, it will rarely if ever need cleaning if handled carefully and kept covered when not in use. The outside surface can be cleaned without danger of damaging the coating. Loose dust on the inside surface can be blown off or lightly dusted with dry cotton.
Pinholes and minor surface scratches are common in solar filters, however, our multi-coating technique keeps them to a minimum. A "bright" pinhole may cause "ghosting" due to scattered light. If this is seen during observation, the pinhole(s) should be blocked out. Blocking out any pinholes should be done on inside coated surface. Hold filter 1-2 feet in front of a standard 60-100 watt "soft white" light bulb. Blocking can be done with a fine point felt marker, small drop of paint, typing correction fluid etc. The touch up procedure will not degrade the optical performance. It is not necessary to touch up any small pinholes that do not cause image problems. There is no danger if some small non light scattering pinholes or minor scratches are present. All filters are tested for safety before shipment.
R-G Solar Film: As with any high quality coated optic, clean coated surface only if absolutely necessary. We recommend using a compressed air blower to remove any loose dust particles. If more rigorous cleaning is required, we recommend using antiseptic alcohol (Isopropyl-rubbing alcohol) and soft tissue wipes (found in pharmacies). Light wipes in one direction are recommended. Use a new wipe for each new direction.
Pinholes and minor surface scratches are common in solar filters; however, our multi-coating technique keeps them to a minimum. A “bright” pinhole may cause “ghosting” due to scattered light. If this is seen during observation, the pinhole(s) should be blocked out. Blocking out any pinholes should be done on the surface facing the telescope. Hold the filter 1-2 feet in front of a standard 100 Watt “soft white” light bulb. Blocking can be done using a thin black felt tip marker. There is no danger if some pinholes or minor scratches are present, and the touch-up procedure will not lessen the optical performance. If multiple large pinholes (5-10) are visible, we recommend disposing of the film. Please note wrinkles are common and will not degrade the performance of the filter.
Black Polymer Solar film: One layer design with absorptive filtering material spread throughout substrate. Clean same as the R-G solar film.
When using low magnification the image may appear bright in some telescopes with optical density 5 filters. Color or polarizing eyepiece filters can be used in addition if desired. The higher the magnification, the dimmer the image will become. Binocular filters have a denser coating since high magnifications are not used.
SOLAR PHOTOGRAPHY:
All of our standard glass and Polymer solar filters are coated to a neutral density of 5, which reduces the light about 100,000 times. Depending on the aperture and focal length of your telescope and "seeing" conditions, you will need to experiment to find the best exposure time for your equipment. We recommend starting with a 100 to 200 ISO film such as Kodak Ektachrome color slide film.
At prime focus, start with an exposure of about 1/250 second using the above or similar film. Experiment with different shutter speeds as well. When using higher magnifications, longer exposures will generally be necessary. Be sure to keep notes on how each frame was exposed so you can compare after the film is processed. Try experimenting with other films as well. If you are a beginner in astrophotography and need further information, there are books available that cover this subject completely. These books can be found at your local bookstore or library and from suppliers listed in the popular astronomical publications.
TYPE 3+: These filters are designed for "seasoned" Astro-photographers for use with very fine grain films without the necessity of increased exposure times. The transmission is about 1/100th of 1% and should not be used visually, except when focusing through the camera.
Please contact Thousand Oaks Optical for more information on our 3+ Solar filters
Do not be discouraged if your first attempts at solar photography are less than desired. The sun is very difficult to photograph because of poorer "seeing" conditions caused by unavoidable heat currents inherent with daytime viewing. The highest possible resolution for any land based telescope, regardless of location, is about 1 arc second. Ideal seeing for any location will be available less than 5% of the time. During bad seeing conditions, it may help to "stop down" full aperture filters over 5".
Storage:
The filter and any extra R-G solar film should be stored in a manner as to avoid dust or dirt collection on the filter itself. A well sealed plastic bag, stored in a container works well in achieving this protection.
