new scope massive guiding issues

[iwols]

just upgraded my scope but now have massive guiding issue,started when i got egg shape stars with the new scope,so i fitted an oag instead of my st80/qhy5 guide camera,made new profile in phd2 but not guiding at all,so close sgp down straight away,my telescope is 580mm focal length on a heq 5 mount,polar alignment is ok as i havent altered it from my ed80 see below

 

 

 

[Davey-T]

A log is always good if you've got one.

If you set the thingy that shows guide pulses on the graph you can see if it's actually sending any, max RA duration of 2500  should be more than enough.

Dave

[iwols]

wheres the log file please

[Anthonyexmouth]

how are you doing your polar alignment? you say it hasnt changed but changing scopes could have nudged it. 

[vlaiv]

Ok - you have PHD2 point you to where problem is.

It says:  Max RA is preventing it to give guide commands.

I'll explain what it means. Your max RA is set to 2.5s. Your guide rate is for some unexplained reason set to x0.1 of sidereal.

Let's suppose that your mount needs to do 2" correction in RA, how will it do it? It will issue pulse long enough so that mount moving at x0.1 of sidereal speed has enough time to move said 2". How long is that? Sidereal rate is 15"/s. You set your guide speed to be x0.1 of sidereal, so your guiding speed is 1.5"/s. For 2" correction it will take it 2" / 1.5" = 1.3333s.

Since you have your max RA set to 2.5s if mount needs to move for longer than 2.5s PHD2 will ignore such movement. With your current guide speed this translates to deviation of 3.75". So if your guide star goes off from RA base line more than 3.75" - PHD2 will assume that you don't want to correct that - your max RA duration is set in this way.

You have one more additional setting to complete the picture - you've set your hysteresis parameter to 90! Hysteresis parameter is used to specify how much previous measurements to take into account when doing correction - it's a sort of lag to avoid correcting on small seeing induced errors - only when it's confirmed that mount is drifting away - PHD2 will act. You have it set on 90 - meaning it will take a long time to "confirm" that mount is moving away from base line in RA. By the time PHD2 confirmed this with said hysteresis parameter - RA has already gone past 3.75" distance from base line and PHD2 can't do anything but tell you - I will not correct it now because you told me so! (and display that helpful message )

Since you are running Heq5 mount, how about setting following parameters:

Guide speed set to x0.4 in both RA and DEC

Aggressiveness to 80%

Leave Max RA and DEC at 2500

Put hysteresis back to 10%

Put both RA and DEC min mo to 0.4 with this guide camera and guide focal length.

Take dark library for guide camera, recalibrate at DEC 0 (use 16 steps for calibration) and see how mount behaves.

 

[iwols]

thanks will try this ,is that correct?

 

where is the guide speed for ra and dec actually set please

 

[vlaiv]

22 minutes ago, iwols said:

thanks will try this ,is that correct?

 

where is the guide speed for ra and dec actually set please

 

It's in EQMod control panel under guiding params

[iwols]

is this it top right ra dec pulseguide setting thanks

[kens]

8 hours ago, iwols said:

thanks will try this ,is that correct?

Under the Help menu you should have an option to Open Log Folder. You ill find your logs there. Find the one with the right date and named as a Guide log (not Debug log). If it is large you might need to Zip it first to attach it.

[Skipper Billy]

Useful document here that might help you..

2nd item down on this page

https://sites.google.com/view/astro-imaging/how-to

[vlaiv]

8 hours ago, iwols said:

is this it top right ra dec pulseguide setting thanks

Yes, those two

[cjdawson]

Ok here's a few things that I think would be useful....

 

1. make sure that you have good polar alignment.   This was my main frustration with PHD in the past, the further out the harder it needs to work.

2. Throw away the calibration data and have PHD figure this out again.  I do this as a matter of course, even though it's not needed, still best to make sure that the calibration is correct and only takes a few mins, versus hours of hassle.

3. Dark frames.   It's worth spending some time doing the dark frame thingy in PHD, off the back of that you can make a bad pixel map.  This in turn will help phd by stopping it trying to guide on a bad pixel rather than a star.

4. Try doubling your exposure time.     2 second exposure should be enough to stop the issues with astmosphere.  The faster the exposures, the more you are chasing the seeing, which simply introduces error's in itself.

[iwols]

thanks guys food for thought ,looks like start from beginning,,looking to invest in a polemaster (i know there are other ways) and guiding wasnt an issue with my ed80,any thoughts on this?

[iwols]

or does my oag want setting up? not sure how,i just placed it in the chain orientation roughly same as main camera????? everything focused ok

[cjdawson]

36 minutes ago, iwols said:

thanks guys food for thought ,looks like start from beginning,,looking to invest in a polemaster (i know there are other ways) and guiding wasnt an issue with my ed80,any thoughts on this?

Rather than spending money on the Polemaster take a look at the polar alignment routine in SharpCap.   I've started using it using my guide scope to do the alignment (rather than the main scope) and it works brilliantly.

 

 

[iwols]

Just now, cjdawson said:

Rather than spending money on the Polemaster take a look at the polar alignment routine in SharpCap.   I've started using it using my guide scope to do the alignment (rather than the main scope) and it works brilliantly.

 

 

which camera would be best on my 550mm scope the main 414ex or my qhy5 connected to my oag cheers

[cjdawson]

21 minutes ago, iwols said:

which camera would be best on my 550mm scope the main 414ex or my qhy5 connected to my oag cheers

I don't think it will matter all that much.

If it's any help, I use a Starlight Express Superstar connected to an ST-80 to do my polar alignment.  This is my Guidescope.    The main imaging I do using my Meade LX-90 and ZWO ASI1600MM.

 

The routine that I've got into is to use SharpCap to perform the polar alignment.  Then switch on the mount and perform an Easy Align (two star alignment)

All of this is done using SharpCap, and the GuideScope.  Once aligned, I then add my imaging camera (it won't physically fit on the scope when pointed at the celetial pole).

At this point, I swtich off SharpCap and switch to SGP for deepsky imaging and PHD2 for guiding.

 

For the polar alignment to work, all that's needed is exposures long enough to see about 15 stars withing 5 degress of the pole.  I can do this no problem with a 4 second exposure.