I'm tracking in after effects for some 3D type to go in to my scene,
the track works but everything is really far away on the 'z' axis and I dont know how to correct it!
I'm figuring its the focal length but how do i change this?
All my scenes are doing the same thing.
Camera Tracking works best if you remove any lens distortion first. GoPro footage can be corrected through there app.
That said, after you track it is important to set an origin and ground plane.
Without complete workflow details and system info there isn't much more that I can suggest.