What does free cam do?

What does free cam and the debug cam do? They dont seem to do anything for me. Also whats the difference between "set free cam" and "toggle free cam"?

Thanks!

As far as I can tell, a recent patch completely broke free cam. . . I haven't been able to activate it recently.

What did it do when it worked?

You had a free flying cam. You used the mouse middle click to adjust the angle you were looking at. You used R and F to adjust altitude, and WASD to adjust position.

E.g

So you could get really close to the units? Closer than the standard zoom?

Exactly, you was able choose any position, even inside planet.

And more to the point, you are able to look "up" at units. Air units would fly over the camera. If you had the time to kill and the artistry (I may have the former, but not the latter) you could take some pretty decent screenshots.