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Doug Robertson's Light Pollution Blocker for NexStar GPS  and CPC Scopes

Some of us find ourselves using our scopes under less-than-ideal circumstances.  If your location has even one local light (a streetlight, for example), you probably strive to block it from your line of sight.  One trick you have likely tried is to use a hood to block the light, but when the scope is pointed high up towards the zenith, light can still shine through the fork arms from behind the scope.

Doug Robertson has devised a simple solution for just that situation.

Start with a piece of thick, dark cloth.  You should test it for effectiveness at night by holding it up to block the offending local light.  Next, point the scope level with the ground and hold the cloth up to the fork arms in the location shown in the picture.  You will want the cloth to drape up and around the bottom of the optical tube so that it will effectively block light when you point straight up towards the zenith.  Note that there will be a little slack to allow the scope to point both level and straight up.  Cut the cloth to the correct width and length similar to what you see in the picture.

Next, get some high-quality self-adhesive Velcro - black is best to match the color of the fork arms.  Cut two sets of Velcro to a length of about 1.5 inches (4cm).  Attach each of the two hook (plastic) halves of the Velcro to the top corners of the cloth, with the long direction

running up and down.  You will need to sew this in place as the adhesive will not hold to cloth.  With alcohol and a lint-free cloth, lightly clean the flat of the fork arms at the points where the top corners of the cloth need to go.  Stick the loop (fuzzy) halves of the Velcro in the center of the flats of the fork arms such that they match the Velcro on the corners of the cloth  Again, remember that some slack is required to allow the optical tube to move freely.

Enhancements might include a more tailored shape along with Velcro on the bottom corners as well.  Perhaps one day an entrepreneur will actually market something like this for sale.

Thanks Doug!

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Michael Swanson
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