G'day Dennis
I did notice a slight shift in the collimation image - the central obstruction and airy disc had shifted ever so slightly, due as you say to the shifting of everything from collimating overhead to pointing at an artifical star at horizontal.
I guess these products are meant to just get you very close, so you can finish the job off on a real star later on
One strange effect I did notice was when I was watching the artifical star image when I'd reached fully racked focus using my StarLight Instruments Feathertouch Focuser.
There appeared a little indentation in the very outer ring of the star image which intruded even further the more tension you applied at the end of focus. I didn't want to try and turn the focus knob any further for fear of damaging something.
But the indentation became quite severe with even the slightest "forcing" of the focus past the end of its travel point.
Any idea what might be causing this strange visual phenomenon?
Cheers