probably nobody in a non-classified situation has built such a thing recently. But if you put enough engineering into it, you could exceed those parameters today. Glass/glass manufacture, lens shaping, etc all improved tremendously. It would be obscenely expensive; every lens would be completely custom, you'd probably burn through hundreds of blanks before you had something worth using, and there are other, easier ways to achieve low-light imaging anyway.

probably? are we just making stuff up now just to prove a point?

I mean, I work with optics, and I know the history of making good glass, so.... no?

the fastest commercially available glass is 0.75-1.0. that means the 0.7 from the glass Kubrik used is still the fastest. i seriously doubt that even someone the likes of Kubrik would have the clout to approach the NRO and ask for whatever the best they have is to shoot a feature film. so your non-classified caveat is kind of pointless.

This is an unnecessarily hostile reading. I just wasn't sure that it was the fastest lens at the time, and I didn't want to say something incorrect.