One other thing to beware of is that some CCD cameras
associated guider chips, as in the SBIG STL-11000, are turned off and “go
blind” for the entire duration of the main image download time. Even the
(somewhat independent), external RGH camera takes a rest, because the main
camera is too busy downloading the image at that moment. Part of the design,
unfortunately – should be live, all the time. Don’t know if it is still that way
in newer models, but I suspect it is.
So, there will be a significant guider bump, due to guide star drift or
bobble, compared to real time guiding performance.
In such case, it is best to introduce a delay between
frames, somewhat longer than the main camera download time, to let the mount
catch up with the guider, to settle down after download completion.
