> the lenses are shaped to better capture terrestrial images, Hubble's optics don't use lenses. Do you have any evidence that KH-11 satellites use lenses? Al

> the lenses are shaped to better capture terrestrial images, Hubble's optics don't use lenses. Do you have any evidence that KH-11 satellites use lenses? Also, I could be wrong, but I thought that the orbits of Keyhole satellites are high enough relative to the primary mirror diameters that the difference between focusing something on the earth's surface and focusing at infinity (columated light) is within the mirror polishing tolerances, so for all intents an purposes both Earth observation and astronomical telescopes have mirrors shaped to focus at infinity. Am I wrong? Is sharper focus what you mean by "better capture terrestrial images"? I thought that the main difference in the mirrors was that image intelligence satellites generally have lower magnification / wider field of view than orbiting astronomical telescopes. If you were to point Hubble at Earth (and not burn out its instruments due to the brightness), I don't think you'd get a less sharp image than you'd get from a mirror ground for image intelligence (assuming same manufacturing tolerances/technology). My understanding is that diffraction and atmospheric distortion dominate the image clarity issues for image intelligence satellites, so there's little to nothing to gain for going narrower field of view / higher magnification.