A couple of years ago, IEEE Spectrum did an article which took the premise that spy-satellite optics could be made that were as good as the Hubble Space Telescope optics (for various reasons, pointing Hubble at the earth "just wouldn't work" :-) They came up with some number like "1 foot resolution" -- and then did some processing on a photograph to demonstrate what that meant. The picture used was a rear view of a VW Bug, with a copy of Isvestia resting on the upper edge of the trunk. Basically, you could tell there was something sitting there, but you couldn't read the headlines :-) Unfortunately, my library is at the moment unindexed, due to a recent move, or I'd include a reference to the article; perhaps someone else here saw it... it covers the physics involved rather well, and lists a lot of the relevant engineering details. _Mark_ <eichin@paycheck.cygnus.com> ... just me at home ...