Awhile back I came across this site on making a 14.5 inch mirror and telescope:
http://www.geocities.com/telescope1999/14-5inch.html
Just how high a power could be used to view terrestrial objects such as a water tower, say 10 miles away? 1000X, 1500X?
Thank-you.
The rule of thumb is 50X for each inch of aperture. so, a 14.5-inch 'scope can use a maximum magnification of 750X.
And I should mention that those are theoretical maximums. Atmospheric conditions will often limit the usuable magnification to around 200X or so.
Interesting Q.E.D.
I do not know how to derive magnification from the following but I wonder how it stacks up to what you posted.
The Keyhole spy satellites the United States uses can supposedly* resolve objects down to 5 inches in size from a distance of roughly 200 miles…that is also through atmosphere even though the satellites are in space.
CITE: http://www.howstuffworks.com/question529.htm
[sub]*-I say ‘supposedly’ because the details on the satellites abilities is classified but most things I have seen suggest at least that capability. They are also in an elliptical orbit so the 200 mile distance is variable.[/sub]