Apologies if this topic has already been discussed.
My equipment is a ZWO asi290mm camera used as an OAG
ASI1600mm-c main camera
ZWO filter wheel
Moonlight autofocusser
PHD2
My sequence completes after autofocus completes successfully even when there are more subs to take. PHD2 autoguiding is paused during the focussing routine which makes sense but it seems that the guide star gets lost when the sequence tries to restart the guiding. SGP then shuts down the sequence. My guiding is very good but I have to select a guide star in PHD2 again and restart the sequence. This happens each time autofocus starts - so usually after a filter change.
I will try to focus the guider better and /or recalibrate next time i get a clear sky but any other ideas will be most welcome. This is the first time this issue has occurred so I’m a bit lost.
First, what mount are you using? If PHD is losing the guide star during an autofocus run (which is a relatively short period of time) that would indicate to me that the mount is not properly polar aligned or there is an awful lot of backlash or periodic error in the mount.
There’s a couple things you can try. First, do you have sequence recovery enabled in SPG, and do you have the option enabled in PHD to automatically choose a guide star? If recovery is enabled then if PHD loses the guide star SGP can try to restart guiding and PHD can choose a new star. You can also try to increase the size of the search box in PHD. If the star is drifting out of the search box during autofocus, a larger search box may help, although you don’t want the search box to be huge.
Hi Joel. Thanks for your reply and sorry for the delay - I’m still waiting on a clear night to have another go. I’m using a Takahashi NJP temma 2 mount which was polar aligned before my sequence started.
I have now set up SGP to autorecover so thanks for that.
I didn’t realise that there was an option in PHD2 to automatically select a guide star - i thought you had to do this manually by hitting ALT+S when you started PHD2?
Anyway, I’ve increased the search box size and i’ll recalibrate. I’m using an ASI120MM mini as a guider and have had issues getting it focussed so i’ll see if i can improve that too.
Hope you dont mind me jumping on your thread but this is what i had last night, created a new sequence from my equipment profile, started sequence but straight after auto focus i get the box come up that said ‘Sequence complete’, not had this before, but looking at the log my guider failed to settle, any reason why that could have happened?
No worries Tony. I’m no expert, but maybe change your settling pixel size in the autoguide control panel? (But now that i think of it, i increased mine to 1.7 pixels from default of 1 in the autoguide control window after the guider took ages to settle previously…maybe that why it failed this time around? hmmmm)
Its worth a try, sometimes sgp throws a wobbly then next day or next time its used its ok, so tonight it maybe ok if not I will look at that pixel size.
The old rule of thumb used to be that a slightly defocused star was just fine for autoguiding. That is not the case any longer. You need make sure that the ASI120 is properly focused. I ran in to trouble several months ago and the issue was simply that the OAG was not focused well enough.
Thanks Joel. I actually have an asi290mm - dont know why i said an ASI120mm - getting too old i think. However, i’ll try to refocus anyway. It’s been a real pain.
I’d heard that it could help if the guide star was slightly unfoused and it made sense because the larger star occupied more pixels that could contribute to determining the centroid. I don’t doubt you but what is the reason that a well focussed star is better?
Chris
Yes, that is the rule of thumb that I operated with for a long time, and I’m not really saying it’s wrong. My above statement is solely based on experience. I wasn’t getting as good of guide results as I felt I should with PHD and my AP1100. I contacted the PHD2 guys and after examining my guide log the first thing they said to do was get better focus on the OAG. As soon as I did that it dramatically improved the guiding.