charles18 In addition to what you're mentioning here, some of which I have noticed myself, I have also seen over the last two nights while monitoring the guiding page, that suddenly the guiding just stops. This is not a function of the seeing conditions. The sky was completely cloudless and moonless and the winds calm. However while the guide star was still very clearly visible there were very significant variations in the guide star appearance and brightness frame to frame.
The guide graph indicates that it is still actively guiding, but in fact it has completely stopped. The solution was simple enough, just re-select the guide star, and restart the guiding. However that also required that I closely monitor the guide graph............
Nothing has changed in my set up or equipment so I doubt this is a new problem, I more suspect it is somehow related to the star lost problem you mention, which I have seen happen far more often.
Last night it first happened while I was halfway through an imaging session on SH2-162....... That target is very low on my horizon so I first wondered if that somehow played a role? But the same thing happened later while I was imaging the Leo Triplets which are much higher, and in the opposite side of the sky. The first time this happened the guide star was in the lower half of my screen, the second time the guide star was in the upper half.
The only other observation I can make here is that I have noticed that when re calibrating on a new guide star the process proceeds West to East as I would expect. Once re centered on the star it then proceeds North to South. However the guiding will then start well before the process seems to have completed, and well before the cross hairs have returned to be centered on the guide star. I have no idea if that is incorrect so I simply mention that as an observation.
