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Settling Time -- PHD2 and Sequence Generator Pro

Astrophotography Beginner
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#1 glatiak

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Posted 19 September 2023 - 09:24 AM

I am getting back into AP after a lengthy hiatus due to a move followed by renovations in our new place. So I have to get the rust filled grooves of experience in my mind cleared out as well as recognize what a couple of years absence has done tot he tools I used to use regularly. My problem is this -- I use both Sharpcap and SGP with a preference for the latter for any serious AP image sequencing. PHD2 is my guide software and I have recently shifted from an external scope to an off axis guider. My mount is a Losmandy GM8/Gemini2, upgraded to the L6 software.

 

When I use Sharpcap, PHD2 runs as a standalone, pausing when I slew -- works fine. But the new and improved SGP seems to insist that it starts and runs PHD2 for a sequence -- not have it running already. I can deal with that. But when I start a sequence, then slew and center on my target, SGP pauses guiding as it should, then tells it to resume. The guide motion display starts up, showing that guiding has resumed. But the sequence just sits, waiting for a signal (?) from PHD2 that it has settled. So at the moment SGP is just decorative but otherwise useless. But I don't find anything that registers as to how PHD2 is to evaluate when the mount has settled and imaging can continue. I see settings in the SGP guiding panel for position stability and time, but that appears to be associated with dithering, which I am not doing (as far as I know). There does seem to be a lot of overlap between the guiding and controlling software -- and I am confused as to what I need to define and how many different places I need to enter it. Would welcome anyone who has a better understanding of the end to end functionality of this key detail to outline all the different places. For some reason the piecemeal help texts are just not working for me.

 

Thanks.



#2 Alex McConahay

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Posted 19 September 2023 - 10:42 AM

I have some experience with SGP........perhaps I can talk about some of these things.

 

>>>>>>But the new and improved SGP seems to insist that it starts and runs PHD2 for a sequence -- not have it running already.

 

I am using the latest save one download of SGP. The info on the latest download does not indicate that there has been a change in its relationship with PHD2.

 

>>>>>SGP seems to insist that it starts and runs PHD2 for a sequence -- not have it running already.

 

I have not seen SGP caring about whether PHD2 is running or not when you start SGP. You do have to configure SGP to use PHD2 as your guider. If you have just set up the system, tell SGP "Tools/Connect all Equipment" and it will connect everything you have configures, then call up PHD, and connect the guide camera and mount, and return to SGP main screen. If PHD2 was already running, it will connect. If not, it will start PHD2 and connect. If you did not already have PHD2 configures properly, and calibrated, then you should go to PHD2 and do that before going forward.

 

>>>>>>>> when I start a sequence, then slew and center on my target, SGP pauses guiding as it should, then tells it to resume. The guide motion display starts up, showing that guiding has resumed. But the sequence just sits, waiting for a signal (?) from PHD2 that it has settled.

 

Which "guide motion display" are you speaking of? SGP has a little one (I never look at it.). PHD2 has its own (where I look). At some point, if the guider is in fact working, the guider will show acceptable guiding----and what is acceptable is configurable. When it does get under a certain threshold, SGP reports that (it is reporting on the status line on right side, bottom of SGP screen the error and how long it thas had that large an error. When it gets below that error (that you specified) for the time you specified, then it should do a bit more ("waiting to settle), and when settled, should start the exposure.

 

Have you seen this happening? Is this where it fails?

 

Remember, it is up to you to set the parameters for "settling" (how long)  and how much error you expect. If you have set them too extreme, seeing itself will prevent "settling."

 

>>>>>But I don't find anything that registers as to how PHD2 is to evaluate when the mount has settled and imaging can continue. I see settings in the SGP guiding panel for position stability and time, but that appears to be associated with dithering, which I am not doing (as far as I know).

 

It is associated with ALL guiding, not just dithering. Go back and revisit and set these very liberally at first-----just to test the system. Liberally means short time and big error. Something easy to achieve. When you are sure it is working, reset to more realistic values. I usually set the “time” to about the time of three guide exposures. I set the acceptable error to the conditions, but at least three or four pixels (or the equivalent in arc seconds). .

 

>>>>>>There does seem to be a lot of overlap between the guiding and controlling software -- and I am confused as to what I need to define and how many different places I need to enter it.

 

Under SGP “Equipment Profile/Guide Tab,” you will find all you need to configure SGP to work with your system. Be sure to apply that configuration before trying to use it. Under PHD2, you will find what you need to configure it. 

 

>>>>>>>For some reason the piecemeal help texts are just not working for me.

 

Yeah, somebody should write a book about it all……

 

At any rate, keep at it. The system (SGP/PHD2) works very well together.

 

Alex




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