Just a short story to let you all know that this theory works in reverse too !
My first scope was a saxon 8 inch f5 dob which I sold to buy my GSO dob.
When the gentleman purchaser came to inspect the scope, the sky of course was clouded over, so I had to demonstrate its capabilities by aiming at distant street lights.
Wouldn't you know fifteen minutes after the buyer handed over the cash and drove away with the scope the clouds had miraculously dissapeared ! (most likely to settle over
his house)
