Thanks Larry.
I told the guy that KH-12s have a massive propulsion unit attached to them and that Hubble doesn't have one. Hubble uses gyroscopes to point in different directions. Hubble is also in a low inclination orbit, which isn't very good for surveillance of the Earth.
As far has focal length goes, I'm sure it is different for the two types of satellites. I've got two 90mm scopes at home, one is a 90mm refracter for astronomical use and the other is a spotting scope. Although they both have a 90mm lense, their optics are setup very differently to accomplish two very different jobs.