I dont know what i did, but assume i did something.

Using Broadcast, camera calibrator, and the Tracked Input 'seems' to be taking in the FOV etc, however once Manual Lens is Off (which i understand its supposed to be off), i have no focus control its all blur. I need to enable it, set a Manual Focus and then i can see the 3d scene but naturally everything else seems to fall apart

I had thought it was an ALT+SPACE+Mouse thing but that seems to be related to Virtual, and in any case, bit stuck - is the focus (of say nothing) coming from the Camera Calibrator?

Edit - ok, found it. There is Focus and Focus Distance. Focus Distance was required and then things worked ok. There is solid documentation on this process? Even specifically for just 1 focal length as a simple point