Observing the Sun safely-excerpt

Some Hints for Observing the Sun Safely.

1. Follow all directions on the sheet from Thousand Oaks enclosed with your solar filter and review the website:

http://www.thousandoaksoptical.com/cleaning.html

Excerpts from the page:

Solar Filter Cleaning Instructions

Glass Solar Filters: Clean only with Isopropyl (rubbing) alcohol and a soft tissue. Apply generous amount of alcohol to the tissue and rub lightly across surface using long strokes. Lightly wipe dry with fresh tissue. Since the coating is on the back side 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 coating. Loose dust on 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 touchup 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.

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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.

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....

CAUTION: 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.

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IMPORTANT POINTS TO REMEMBER

Check filter for any possible damage before each use. Keep the finder-scope covered if not equipped with a solar filter.
Allow telescope and filter to equalize to outside temperature (at least 15 minutes).
Direct sunlight may warm the tube assembly enough to cause internal heat currents that can degrade image quality.
Cover the tube assembly with a light colored cloth.
If possible, do not view over pavement or buildings. Viewing over grass will help avoid surface heat currents.
Point telescope away from sun before removing solar filter.
Do not leave telescope unattended where children or inexperienced adults could point it at the sun without the filter properly attached.
As with any optic, clean coated surface only if absolutely necessary.
"Ghosting" can occur due to internal reflections. If this is a problem, simply tilt the filter slightly. (Glass only)
Do not place your filter up against a smaller telescope. The end of the tube will damage the coating or substrate.
When looking through the focusing tube without an eyepiece, there may appear to be small defects in the coating which are not seen when observing through the eyepiece. This is normal and is not a coating defect or safety concern.

McCarron method for safer telescope pointing (note not infallible):

1. Duct tape a 12inch length of 1/2 in PVC pipe (or similar "bigger than a straw, but small diameter" tubing) to the body of the telescope.

2. Be sure it's aligned to the scope (align to two screws on the Meade LX-200 (see figure below) or sight along the tube and through telescope eyepiece at an object OTHER THAN THE SUN! Never look at the Sun directly through the tube or through the telescope without a proper filter.)

3. Put the solar filter over the end of the telescope before you point the telescope anywhere near the Sun. Make sure the finder scope is removed and safely put away so no one is tempted to use it. Place your hand at the back end of the PVC tube (see figure below). Move the telescope so that the sunlight coming through the PVC tube is centered. (make the tube shadow the smallest possible and the spot-o-Sun in the middle of the shadow the largest possible.)


Not So Good	Better	Best (Yeah!)

4. Look in the eyepiece. It should be there! The more the magnification, the dimmer the image (better), but the more you have to move the scope to keep the Sun centered (harder). If the Sun isn't in the eyepiece, move the telescope slowly N-S, then E-W. Adjust the duct tape accordingly to align the PVC tube to match the view through the eyepiece. (Again - never look through the tube directly at the Sun. Use the shadow on your hand to check the alignment of the PVC tube.)

5. Once you start your impatient viewers looking through the eyepiece at the filtered image of the Sun, step in and recenter the Sun approximately every other viewer. (This can be adjusted to every third, fourth, etc. depending on time of day, time of year, focal length, F-ratio, eyepiece, etc.)

6. Keep emphasizing that no one look directly at the Sun without proper protection.