Originally Posted by
Topcliffe Kid
....Not to forget, the (near vacuum) atmosphere between 60-70K feet and 300+km gives (how minimal) optic distortion, which is avoided, when the optics+camera are dangling under a balloon.....
Surely most distortion will occur in the lower atmosphere where man-made effects (rising heat etc) and natural turbulance exist?
Yes, of course, distortion in the lower atmosphere is highly relevant, though also above 60-70K feet, there is some distortion due to particles. Don't forget, the camera/optics "views" a kind of cone, so the higher up, the more the same optical details do go through a much smaller "beam" of space. IE the same concentration of particles not relevant for optical distortion near earth will have a much bigger impact higher up, in the smaller sized optical cone.
Edit: Have a look at a Chinese spy expert, explaining the advantages of spy balloons (including better resolutions):
CNN reporter asks Chinese official about suspected spy balloon.