Tell PhD to be more tolerant of seeing?

[kirkster501]

Hi all,

I noticed  that PhD2 (2.6.9) seems to be much more fussy about its guide stars and even a very high, almost imperceptible, haze that is very light will set it off chirping and force a sequence abandon in SGP or NINA.  It's so fussy now that if we were to wait for the desert skies it seems to expect then we'd never image anything in the UK.

Is there a way to tell it to be more tolerant - or to tell SGP or NINA to be more accepting of what it is being fed from PhD2????  I must surely have something set wrong since I set this new PC up.  I never recall it being so bad before.  I am forever in sequence recovery mode even with very, very light haze passing by that used to go unnoticed by PhD.

Thanks, Steve

[Gina]

I use the Ekos native guiding and it seems very tolerant of thin cloud and haze.  (KSars/Ekos/INDI)

[sloz1664]

13 hours ago, kirkster501 said:

Hi all,

I noticed  that PhD2 (2.6.9) seems to be much more fussy about its guide stars and even a very high, almost imperceptible, haze that is very light will set it off chirping and force a sequence abandon in SGP or NINA.  It's so fussy now that if we were to wait for the desert skies it seems to expect then we'd never image anything in the UK.

Is there a way to tell it to be more tolerant - or to tell SGP or NINA to be more accepting of what it is being fed from PhD2????  I must surely have something set wrong since I set this new PC up.  I never recall it being so bad before.  I am forever in sequence recovery mode even with very, very light haze passing by that used to go unnoticed by PhD.

Thanks, Steve

Hi Steve,

I normally guide at 1 sec in PHD2 and if there is any bad seeing. guide star lost etc I increase the exposure upto 4.5 secs if I need to. Any higher than this, it's not worth imaging and I give up until hopefully it clears.

Steve

[kirkster501]

Yeah, thanks Steve, maybe I need to lower my expectations and it is just bad seeing.  

[Laurin Dave]

Maybe try increasing the Star Mass Detection tolerance in the Brain Guiding tab

[kirkster501]

Thanks guys for your thoughts.  The sky certainly seemed pretty good but I kept getting the warning chirps from PhD with even the tiniest whisp of passing high level mist for a few seconds, the stars were still perfectly visible through it.

Cannot wait for crystal clear skies in the UK or we'd never get anything done.

[stash_old]

+1 for PHD2 goning haywire with latest version - I suffer the same so I am going to install an older version. Even ran the wizard again same problem. Changing Exp make no difference too. Its gone from very good to a pile of ++++

[Hughsie]

Usually I am guiding between 2.5 - 3s and last week I switched out from using the ASI290mm to a Lodestar x2 camera. I don’t know if this was more to do with the camera change or new PHD2 version but the damn thing kept flashing and pinging away like crazy. In the end I went into the brain setting and on the guiding tab reduced the minimum star HFD pixel size from 1.5 to 1.2 and it merrily went on its way.

John

[kirkster501]

Thanks guys will look into this further.

[almcl]

+1 for Laurin Dave's suggestion to increase the star mass detection tolerance.  80 or 90% may not be too much.

Also might be worth increasing the search region size, so that if a momentary loss of guide star occurs, it gets found again. 

[kirkster501]

All good tips guys, thanks.  I've never had to do these adjustments before but, all the same, will give them a go.

[almcl]

Another thing that occurred after I typed the above is that the current guidance from the PHD2 developers is to get the guide star as sharply in focus as possible.  The old advice about 'soft stars' is no longer current, although it still seems to be repeated...

[MartinB]

Just to reiterate, under advanced settings you can try reducing the target SNR in the camera settings and or increasing the star mass detection tolerance under guiding.  This should work but it is worth reverting to more stringent settings when the guide star and the seeing allow to ensure optimum guiding.

[michael8554]

12 hours ago, Hughsie said:

reduced the minimum star HFD pixel size from 1.5 to 1.2 and it merrily went on its way.

That's a bit counter-intuitive.

The HFD selection prevents PHD2 locking onto a hot pixel.

So normally it's set to a figure bigger than 1, but less than the average HFD of your guidestar - is yours 1.5 ?

In fact Lodestars often have close clusters of hot pixels, so lowering the HFD would get you close to guiding on a cluster.

Michael

[david_taurus83]

If using a ZWO 120mm at high gain i found PHD will auto select the faintest of stars to guide on. This nearly always produces a wobbly star on nights of poor seeing. The biggest improvement was to go to low gain of 10/20 and PHD will then always pick a bright star without saturating and have a SNR of 200/300. I started a thread on this a while back.

[StuartJPP]

My mantra is, if it ain't broke don't fix it....i.e. unless PHD2 is giving me actual problems I stick to the "old" version, which works, rather than risking a new version of unknown quantity.

Last time I was imaging it was nearly a year since the previous session and things just worked.....last thing I want to do is update all the software in anticipation of a clear night.

 

[alan potts]

Recently I have to agree with Dave above, it seems to select very faint stars and to also agree with the Op, it is a lot more fussy then it was this time last week. It updated a few days ago. I select my own star and I would say guiding is very good some night. When it's not then it is just conditions. Last night was a night of thin cloud that sadly just got thicker.

Alan

[kirkster501]

On 17/10/2020 at 11:24, david_taurus83 said:

If using a ZWO 120mm at high gain i found PHD will auto select the faintest of stars to guide on. This nearly always produces a wobbly star on nights of poor seeing. The biggest improvement was to go to low gain of 10/20 and PHD will then always pick a bright star without saturating and have a SNR of 200/300. I started a thread on this a while back.

As it happens, it is a ASI 120M mini guider that I am using here in the context of this thread, it that is what you mean.

[david_taurus83]

2 hours ago, kirkster501 said:

As it happens, it is a ASI 120M mini guider that I am using here in the context of this thread, it that is what you mean.

Try it at a low gain. It will still pick up stars but the brighter ones and will auto select them.

https://stargazerslounge.com/topic/352498-phd-choosing-poor-stars-asi120-mini/

[stash_old]

Went back to my old version of PHD2 (2.6.8) problems all disappeared so ,for me, 2.6.9 is a no no,no go !

[kirkster501]

Just to close this off.  I have more accurately focused the guidecam and increased the star tolerance.  Everything seems much better now.

Just a QQ.  How long are the PHD exposures?  Where is that configured?  I know there is the slider thingy and I have that set at 2.5s usually.  But this is how often PHD takes an exposure right?  Not the exposure itself?

Many thanks.

[AKB]

IIRC, that is the exposure.  Given that you probably want to guide the mount as frequently as possible, there should be little reason for it to be otherwise. 

[geeklee]

I guess I think of it as both. That drop down box for time is the exposure, hence longer to beat seeing issues. 

There's a brightness slider but I believe this is purely cosmetic for the view. 

Edited November 7, 2020 by geeklee