Ken - I am having unexpected frame restarts in SGP and I’m trying to establish the root cause. I use a well-behaved Paramount MX with ProTrack. I have traditionally used PHD2 and standard hysteresis algorithms, with 8-ish second exposures and a SGP frame restart of a few pixels.
I changed the algorithm to Z-filter in PHD2, with 2s x4 setting. The outcome is that the real-time graph thrashed about with seeing but the actual guider corrections were fewer and smaller.
As soon as I used Z-filter, however, - I had several frame restarts.
So - my obvious question is, how does SGP establish a frame restart? I’m wondering if it is using the last centroid error measurement and being caught out?