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Message: <blockquote data-quote="Binastro" data-source="post: 3577342" data-attributes="member: 111403">I read the name on a hotel 11 miles away with a selected 1970s Celestron 20x80, Japanese made, firmly resting on two telephone books on the window ledge, plus a 7x binocular behind it, giving about 140x.A fellow in New York had an 11 inch long focus refractor mounted on a truck giving views of the people atop the Empire State building. I think this may have originally been a 13 inch refractor? I think he charged a small amount.My 12.5 inch Dall Kirkham was no slouch either terrestrially.Horace Dall's camera obscura 110mm f/30 corrected for 4 colours photographed a church gutter about 6 inch wide from 17 miles.There are views  from the U.S. from maybe 40 miles? of distant observatories with a large scope.Some military Maksutov systems can apparently lock on a car door handle at 90 miles. Probably specular reflection.And photograph golf balls from 80,000 ft. while travelling at more than 2,000 mph.Also the ability to tell if it is cow or a bull from shadows.Or 4 inch objects from 250 miles oblique.The 144 inch f/8 Baker lens for 28 inch x 28 inch film is used to fix asteroid positions to 1/50 arcsecond accuracy.But for normal use the 100mm f/9 ED refractor sounds fine, or a larger version, which might get cumbersome.</blockquote>