I just introduced a new feature in 3.5.1-beta (nightlies) that you may be interested in testing.
This attempts to improve an issue I've been having, and I've heard others have seen, where guiding drift "spikes" can occur, e.g. right after autofocus sessions. For instance, see this
Analyze screenshot
.
What's happening is an interaction between capture, guiding and autofocus. When I image, I enable autofocus on filter change, and I also suspend guiding during autofocus. [The bottom checkbox on the focus tab in the settings sub-tab says "suspend guiding", and using that makes sense to me, as guiding and autofocus would seem to interact poorly with each other]. Unfortunately, though, without guiding, and with the focuser pumping in and out, the guide star can wander away from its target position during the minute or two of an autofocus session.
Thus, occasionally during my imaging sessions, my capture sequence changes filters, then autofocuses, and when capture restarts, the guide error is significant and it can take several guiding iterations to correct, during which the image is being captured. Further, if the target is sufficiently offset, or if the guide star wandered out of the reticle, the guider might fail to even find the guide star, and would then be restarted by the scheduler. A new guide star will be found, possibly with a significant positional offset from the origin image coordinates (and likely doubled stars). This happens shortly after the red and green focus sessions in the above screenshot link, and is the cause of the red RMS line spiking up.
I have attempted to fix this with a new capture control, and you can see the improvement in
this screenshot
.
The main change is this
new capture-tab checkbox
that, when enabled, causes the capture process to wait for a low guider offset before starting up a new image capture. This might be, for example, 2 arc-seconds (the default) as in the screenshot. Thus, if after focus is completed and the guider restarts, if the guide star is offset by 15 arc-seconds, and requires 4 guider iterations to get back to a < 2 arc-second offset, capture will wait until those guide iterations are complete.
In addition, Analyze now has a new graph. In the capture line below the Statistics graphs, there's a capture RMS graph, which plots the guider drift, but only uses samples when an image is being captured -- so it more properly reflects the "important RMS" that will be baked in to the captured image. You can see that in the
2nd screenshot above
. I may ultimately remove the above rms (on the Guide line) which reflects ALL guide iterations (even when no image is being captured). For now I left them both in. I'd recommend using the new
capture-only rms--which I believe measures what you want to see.
As always, please feel free to send bugs/suggestions.
Hy