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I think we're getting lost in the forest.
Ideally the target star MUST be visible somewhere in the FOV of BOTH the guide camera and the imaging camera. The FOV of the imaging camera is restricted by the "slit aperture", so the target needs to be accurately placed within the FOV to be seen.
The "registation" between the two is the issue.
(The problem is a little more complex if you only use an OAG - then you need to work out plate scales and off-sets)
Once the target is on a wide slit then you should select the same target star in the guide FOV to guide on. This can be done in PHD with or without Al's reticle.
The real issue is to be able to do this quickly and repeateably. So if you know WHERE in the guide FOV the target should be placed (X=, Y=) to position the star on the slit, you can use this setting every time.
The use of Al's reticle only makes this more intuitive and easier.
Ken
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