phil, the problem with very fast cameras is the phenomenon of "noise." If I set my ISO to 3200, a good Milky Way exposure will take 20 to 30 seconds, but the image will be pretty clean. If I set it to 12,800 (I think that is the number), it takes an equally-bright image in about 8 seconds. But the higher ISO is infected with a lot of electronic noise that is very hard to edit out.
Having said all of that, your question is about approximating what the eye sees. I think that a 3200 shot at five seconds might do that much. But the joy of the digital SLR is the ability to take shots that are better than the eye can see. That feature has added so much to our enjoyment of boondocking.
Based on absolutely no factual information, my guess is that the military folks have high ISO cameras that take flawless snapshots at night, but they are not releasing those tools for public use.
