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"PHD2 Problem - Message: PHD2 is unable to make sufficient Corrections in Dec"

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#1 vaticanaddict


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Posted 25 January 2021 - 02:20 AM

Hi guys.

Yesterday I installed/updated PHD2 to the 2.6.9dev3 version (Beta Multiple Star Guiding). 

I also installed a new ZWO EAF Focuser (but haven't re-balanced yet).

Last night I encountered the following Message: "PHD2 is unable to make sufficient Corrections in Dec. If you just ...a meridian flip...check to see the Reverse Dec output option on the Advanced Dialog Guiding tab....".

When first launched PHD2 last night - I could see the multiple green circles and Guiding was perfect for about 3 minutes.

Then I got the Message.

I checked the Advanced Settings tab and found the "Minimum Star HFD (pixels) was set to 0.0. For some reason I thought that was the issue and changed to 0.5. (now I get to see less green rings)

Also - my Dec. Guide speed was set to 0.10x (which is pretty low).

I don't know if this is the reason but after changing the HFD it worked from then on pretty good.

However I have been doing some reading and it seems that the HFD is not the issue here.


Do you know of any problems with the New PHD2 2.6.9dev3 version? 

Can it really be the un attended change in Balance?

What is the reason for the abovementioned Message?

Any ideas?





#2 happylimpet


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Posted 25 January 2021 - 03:03 AM

You dont want the minimum HFD too low or it might mistake hot pixels for stars, which messes things up.  A value like 2 works for me, but it depends how sharp your stars really are - too high and it wont recognise them.


Having the guide speed at 0.1 could be part of the reason. Theres a maximum adjustment setting somewhere and if PHD feels it needs to move more than this, you get the error. Having a slow guide speed will make this more likely as corrections need to be longer. Maybe change to 0.5. 

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#3 Stelios


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Posted 25 January 2021 - 03:23 AM

Can you post your *guide* (not debug) log from PhD2? 


What you fixed should have made little difference, but you should revert it, as it may prevent you from guiding on a small tight (Lorenzian shape) star, which may be needed in star-sparse regions. A dark library (which you should have taken--PhD2 prompts you to) will prevent your guiding on hot pixels, as will "auto-select star."


Also a screenshot of the full error message (use Snip if using Windows) would help. 


If, in the Guiding Tab, you have the "Reverse Dec output after Meridian Flip" checked, then *un*check it. *Were* you performing a Meridian Flip when this error occurred? Based on your description, I sort of doubt it. 


It is a good idea to recalibrate if you didn't do already. Possibly you rotated the guide camera when installing the auto focuser. 

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