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PHD2 options

Anthonyexmouth

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Stub Mandrel

Stub Mandrel

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That guide star line is useful.

As cloud crept in last night long before it obscured Cygnus (my target area) the star quality lines dropped down and guiding started to degrade severely. Without the star quality lines (and the obvious thicker cloud approaching) I could easily have assumed some fault in my setup and spent ages chasing better guiding that wasn't actually possible.

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Anthonyexmouth

Anthonyexmouth

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7 minutes ago, Thalestris24 said:

Both!

That one - 232053 - seems to show no guiding corrections and a lot of drift over time so I presume it was the unguided one?

these are the only 4 files that are dated for last night

PHD2_DebugLog_2018-08-04_232053.txt

PHD2_GuideLog_2018-08-04_232053.txt

PHD2_DebugLog_2018-08-04_221119.txt

PHD2_GuideLog_2018-08-04_221119.txt

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Thalestris24

Thalestris24

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9 minutes ago, Thalestris24 said:

Both!

That one - 232053 - seems to show no guiding corrections and a lot of drift over time so I presume it was the unguided one?

Tell a lie - it was zoomed out because of the large drift:

log1.thumb.JPG.bcd8ee19c0bd21651924be4435b8fef7.JPG

Something strange going on here!

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Thalestris24

Thalestris24

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Both seem to be diverging at quite a rate...log2.thumb.JPG.07cf0627e30a0a21a76a364fa8560b40.JPG

I'm not sure what's going on here... There are no guiding corrections (even though it says 'guiding') but I'm not certain what that square wave is - it looks like some sort of electrically induced signal. I downloaded the log viewer from the openphdguiding web page and hadn't used it before so maybe I'm missing something.

There are lots of short recordings - max ~2mins. Were you getting any warnings from PHD2 on the screen?

 

 

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Thalestris24

Thalestris24

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Here's what you might expect to see. This is from the beginning of June (prob the last time I tried any imaging, lol):

Mylog1.thumb.JPG.9658179370ff5290d15101bde53f88b6.JPG

Together with calibration:

Mycalib.thumb.JPG.d88df7cd346c80e1577b7f82c4d8b0ef.JPG

Although my guiding wasn't great (never is here!) you can see corrections corresponding to peaks/troughs. So everything was working ok. There aren't any corresponding corrections on your logs as far as I can see.

Louise

ps I see you have backlash compensation of over 2secs - probably best to disable that!

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Stub Mandrel

Stub Mandrel

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29 minutes ago, Thalestris24 said:

Both seem to be diverging at quite a rate...log2.thumb.JPG.07cf0627e30a0a21a76a364fa8560b40.JPG

I'm not sure what's going on here... There are no guiding corrections (even though it says 'guiding') but I'm not certain what that square wave is - it looks like some sort of electrically induced signal. I downloaded the log viewer from the openphdguiding web page and hadn't used it before so maybe I'm missing something.

There are lots of short recordings - max ~2mins. Were you getting any warnings from PHD2 on the screen?

 

 

The guide pulses are too long so tey look odd. I think aggression is too low and the mount can't keep up?

It looks like DEC correction was switched off.

Strong correlation between RA and DEC errors suggests bad PA, but possibly the guidecam has rotated, perhaps not screwed in  tightly?

 

 

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Thalestris24

Thalestris24

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1 minute ago, Anthonyexmouth said:

why  would the polar alignment error be so different in the 2 logs? nothing changed on the mount between logs

Both logs show a severe divergence between RA and DEC and which can't be corrected. So there must have been something fundamentally wrong - balance, extremely poor PA, or something else. I think I'd go back to basics here. Check the power supply. Check that PHD2 is talking to the mount, nothing snagging, Eqmod setup correctly etc. etc.

Louise

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kens

kens

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Your guide rate is way too low at 0.1x sidereal. Increase it to at least 0.5x and as much as0.9x

Edit: After you change the guide rate you will need to do another calibration

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Thalestris24

Thalestris24

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7 minutes ago, kens said:

Your guide rate is way too low at 0.1x sidereal. Increase it to at least 0.5x and as much as0.9x

Edit: After you change the guide rate you will need to do another calibration

Where does it say that? How did I miss it....

Reading how to analyse the guide logs is useful https://openphdguiding.org/Analyzing_PHD2_Guide_Logs.pdf

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Thalestris24

Thalestris24

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Hiya

Disable any backlash compensation

Don't use dithering for now

Don't use a hub - make sure you have a 'high speed' dedicated usb 2 connection for your guide cam (or usb 3 if it's a newer version). Always use a high quality shielded usb cable for the guide cam which is not too long. About 3m is max (tho might work with 5m)

Enable the star profile

With the 9x50 finder make sure the objective lock ring is tight (I seem to remember having some problems with this once upon a time. I keep it taped in place now :) )

Make sure you have 180mm for g/scope focal length and use the 'calculate' calibration step time tool

Use max guide speed in eqmod (you can adjust this later once you are up and running reliably)

I guess you want to get everything set, making sure all cables and connections are ok

Make sure you are pointing true north on a level and firm base - away from any wind gusts!

Make sure you are balanced in all three axes - RA, DEC, vertically

Set the balance slightly east-heavy by adjusting the counterweight (you could skip this until you've confirmed everything else is running as expected)

You may need to wait for scope temperature stabilisation but probably not a biggy this time of the year

At this point you could try out the Polar Drift Align tool - I've never used it but providing you can see the Pole Star you can use it to get a rough polar alignment

Calibrate (at ~30 deg DEC) (if you have a lot of backlash, PHD recommend moving the scope north for about 20s first to take up the slack)

Do more accurate Drift Alignment with the drift align tool

Calibrate again

Slew to your target

Optionally platesolve (you would expect this to be quite a small correction otherwise there may be something wrong. If you find the scope moving like 15 deg then  there's something wrong like time or lat/long)

Hopefully start guiding then imaging (it might be an idea to run the Guiding Assistant for a few minutes as a sanity check)

Fingers crossed! Monitor the guide star profile - try and find a star with high snr (100-ish is good!) but it shouldn't be clipped using a 2s exposure

Monitor the star target to make sure it's a tight cluster around the centre. Exactly what you can achieve will depend on the seeing

Make sure you don't have any excessive drift in RA or DEC. If you do, you're probably not balanced correctly and/or your calibration/PA hasn't worked properly

Display the guide graph with guide corrections and monitor it to make sure things are going as expected. Keep an eye out for any warnings/error messages

That's about all I can think of right now. Hopefully I've not said anything wrong or missed anything important out...

Louise

 

 

 

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Thalestris24

Thalestris24

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2 hours ago, kens said:

Your guide rate is way too low at 0.1x sidereal. Increase it to at least 0.5x and as much as0.9x

Edit: After you change the guide rate you will need to do another calibration

Oh yeah, found it now, duh - how did I miss that! (I actually have been to Specsavers...). Even so, unguided performance shouldn't have been that bad.

Louise

 

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Stub Mandrel

Stub Mandrel

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2 hours ago, kens said:

Your guide rate is way too low at 0.1x sidereal. Increase it to at least 0.5x and as much as0.9x

Edit: After you change the guide rate you will need to do another calibration

You know, I thought that as soon as I read this:

29 minutes ago, Thalestris24 said:

Use max guide speed in eqmod (you can adjust this later once you are up and running reliably) 

In fact I thought "I bet that's why his scope can't keep up..."

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Thalestris24

Thalestris24

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Your RA and DEC rate sliders should be to the far right to start off with. I would also clear the alignment data if your using platesolving. In any case, if you are setting up fresh every time you'd need to redo the star alignment each time. Using platesolving, I've never bothered with star alignment - it's redundant.

Louise

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