Issues with guiding

[Iem1]

Hey guys,

Just returned from my first night out with my new equipment that I have finally had a chance to use after months of it collecting dust! I used my ASI airplus and guiding setup for the first time tonight, all went well...except for the guiding part

Equipment used:

WO Z73 430mm, Canon 600D, EQ6 R Pro, ASI air plus

Guiding:

ZWO 120mm mini camera/scope 

I focused and PA well via the ASI, platesolved and was able to very accurately find my target for the night, but my guiding would only last maybe 20-30 seconds. 

I believe I have everything wired correctly, I use an EQ Mod cable.

Here are some screenshots;

 

 

The guiding would usually start around 0.10' in RA and Dec, sometimes lower, it might maintain for around 10-20 seconds but would always begin an upwards spiral. I couldn't get a clean 2 minute sub.

Struggled with getting a good focus with the guide scope too.

Any ideas what might be the cause? This is my first ever outing with any sort of guiding and the ASI air, so I very well could have messed up the most simplest of things.

It almost seemed like it simply wasn't guiding, that it had set parameters but was unable to actually guide within them (if that makes sense) and so with the natural movement of the mount it drifted out.

Still had an absolute blast learning, even with not being able to collect data, the ASI air is unbelievably efficient!

Thanks for looking guys.

[Iem1]

Edit: In regards to the guide cam, I only have a connection from the USB port (straight to the ASI Air), I am not using the ST4 port...should I be!?

[Simon Pepper]

Hi Lem

i have - similar setup. What guide scope are you using? That focus is fine by the way. I see you have a star tracker too and I can’t see the RA line have you left the guide the RA only box on? Couple other things. Clear calibration every time depending on guide scope you may need to lower the steps let me know

Thanks

 

[ollypenrice]

This rings alarm bells for me straight away: 'I focused and PA well via the ASI.'  Does this mean you believe in your PA because some software tells you its good?  I've had plenty of experience of software not being accurate in this regard. Once aligned I would do a simple drift test like this: point the scope towards the celestial equator in the south. Set up a 3 minute sub and, during this exposure, track at the slowest possible speed for 1.5 minutes one way in RA and then 1.5 minutes back again. This will produce an outward star trail and a return trail. If the PA is good the star trails will overlap, producing one single line. If PA is out you'll get a shallow angled vee. This test is software-free and direct so it can be believed in implicitly.

Being suspicious of all things software I also prefer to guide by the simplest means possible and that's by the old fashioned ST4 cable. This means no 3rd party software, just the camera, the mount and PHD involved.

Olly

Edited August 7, 2022 by ollypenrice
typo

[Simon Pepper]

29 minutes ago, ollypenrice said:

This rings alarm bells for me straight away: 'I focused and PA well via the ASI.'  Does this mean you believe in your PA because some software tells you its good?  I've had plenty of experience of software not being accurate in this regard. Once aligned I would do a simple drift test like this: point the scope towards the celestial equator in the south. Set up a 3 minute sub and, during this exposure, track at the slowest possible speed for 1.5 minutes one way in RA and then 1.5 minutes back again. This will produce an outward star trail and a return trail. If the PA is good the star trails will overlap, producing one single line. If PA is out you'll get a shallow angled vee. This test is software-free and direct so it can be believed in implicitly.

Being suspicious of all things software I also prefer to guide by the simplest means possible and that's by the old fashioned ST4 cable. This means no 3rd party software, just the camera, the mount and PHD involved.

Olly

I think you are right to suspect as I can one day the PA accuracy on AAP is not perfect but it’s good enough. Also AAP runs PHD I thought so there is no additional software here other than ZWOs OS? ST4 is dated now the OP has everything correct with cables I think the issue is RA only is on in AAP. Thanks 

[Iem1]

1 hour ago, Simon Pepper said:

Hi Lem

i have - similar setup. What guide scope are you using? That focus is fine by the way. I see you have a star tracker too and I can’t see the RA line have you left the guide the RA only box on? Couple other things. Clear calibration every time depending on guide scope you may need to lower the steps let me know

Thanks

 

Hi Simon,

I am using the ZWO Mini Guide Scope (120 mm). 

I have a Sky Guider Pro star tracker, but I use my EQ6 R Pro for deep sky now.

I think I saw that option (RA only) whilst tinkering around with the settings and I believe it was off. Although I did go back to check after I couldn't get the guiding to work and I could not for the life of me see the setting again! So maybe I managed to switch it on somehow 

44 minutes ago, ollypenrice said:

This rings alarm bells for me straight away: 'I focused and PA well via the ASI.'  Does this mean you believe in your PA because some software tells you its good?  I've had plenty of experience of software not being accurate in this regard. Once aligned I would do a simple drift test like this: point the scope towards the celestial equator in the south. Set up a 3 minute sub and, during this exposure, track at the slowest possible speed for 1.5 minutes one way in RA and then 1.5 minutes back again. This will produce an outward star trail and a return trail. If the PA is good the star trails will overlap, producing one single line. If PA is out you'll get a shallow angled vee. This test is software-free and direct so it can be believed in implicitly.

Being suspicious of all things software I also prefer to guide by the simplest means possible and that's by the old fashioned ST4 cable. This means no 3rd party software, just the camera, the mount and PHD involved.

Olly

Very true! I did not confirm my PA, I trusted in the software.

truth be told, i still haven't even calibrated my polar scope, or ever used it! Only ever used the hand controller and now the ASI to PA

I would have thought, that with fully functioning guiding, having an accurate PA is less important as you have constant correction from the guiding? Or is a bad PA too much for the guiding to correct? 

looks like we have a few clear nights in a row so I'm looking forward to getting back out there to have another go!

Thanks guys

[Simon Pepper]

You need a good PA guiding and PA are separate anything with a smiley face will be good in the AAP but this does depend on focal length. There is another setting something about restoring from last session make sure that’s off as well and make sure when calibrating that the steps count up to at least 12 West and back and 12 north and back. 

[Elp]

What are the settings under the telescope icon in the app? Sounds to me like the tracking isn't switched on or the guiderate isn't set at the right speed.

PA in asiair is usually fine though sometimes I still get tracking issues, I tend to slew to target then calibrate there and always recalibrate when changing targets or starting a new session.

[Iem1]

21 minutes ago, Simon Pepper said:

You need a good PA guiding and PA are separate anything with a smiley face will be good in the AAP but this does depend on focal length. There is another setting something about restoring from last session make sure that’s off as well and make sure when calibrating that the steps count up to at least 12 West and back and 12 north and back. 

Here's my PA according to the ASI (I did improve it a bit more after this was taken)

I found that setting after tinkering and switched it off to try it. But I do not recall it actually calibrating properly, in a video I watched it did some sort of North/West steps in which it calibrated. Mine did it briefly initially, but never again after redoing the calibration for some reason.

21 minutes ago, Elp said:

What are the settings under the telescope icon in the app? Sounds to me like the tracking isn't switched on or the guiderate isn't set at the right speed.

PA in asiair is usually fine though sometimes I still get tracking issues, I tend to slew to target then calibrate there and always recalibrate when changing targets or starting a new session.

I can't recall. Perhaps these were the issue if you have to manually turn on guiding and set guiderate in a separate panel. These did not even occur to me. First night out in a few months so I was very rusty!

Some other screen shots I grabbed that may hold some info:

(eventually turned auto restore calibration off)

(Early on in the process, before I attempted guiding I think)

[Simon Pepper]

If you have issues again tonight bosh it here I’ll be out trying to figure out my mosaic that fantastically failed last night as well

Edited August 7, 2022 by Simon Pepper

[Varavall]

8 hours ago, Iem1 said:

I believe I have everything wired correctly, I use an EQ Mod cable.

Here are some screenshots;

Hi

Just a thought. I have seen PHD2 graph similar to what you have a couple of times on my rig. One was caused by a cable snag and the other by one of my cats trying to sit on the mirror end of the Newtonian.

[Elp]

The PA looks okay, you can sometimes get changes to it whilst imaging if your equipment isn't bolted down securely, mainly from the mount head (less susceptible in bulkier kit), Dec and Ra balance also is critical at times.

Did you watch the guiding calibration all the way through, at the RHS icons on the guiding screen, the top one you can press this and see the graph calibration angle, the Dec and RA should be at 90 degrees to each other if it's calibrated right, there is also a clear button under this which you can press so you can recalibrate. If you watch the guide calibration you should see the main guide star go one direction in a straight line, then back again along the same line (E to W), then switch 90 degrees (N to S) and do the same. The circled guide star you will see moving away from centre then back to centre and the routine should finish in the same position as when it started. If your tracking is on and at the correct sidereal rate speed your guide stars should remain on screen and not move.

Anything like wind, knocks, snags, motor issues you'll see as spikes in the guide graph.

Take a look again at the settings under the telescope tab. On the rare occasion I've found the sidereal rate to be off after calibration, streaking stars in a uniformly straightish line usually are the symptom.

You do get issues from time to time, I tried the elephant trunk the other night and couldn't get a decent sub it was fairly high in the sky where Ra and Dec adjustment kind of overlaps due to requiring minimal movement near the zenith so my balancing was probably causing an issue, I didn't carry on with that target at the time, I also knew it probably wasn't going to work as the E-W calibration was taking 20 steps which is excessive, usually it completes within 5-10 steps each way. Moved to M31 much lower in the sky and it was fine. Sometimes you just need to persevere or try another target.

[ollypenrice]

If your PA is out you'll get field rotation around the guide star, however well the guide star is held in place by the guider. In a nutshell, the guider can only do so much. 

Olly

[newbie alert]

 

ST4 guiding maybe old but the op is using a pulse guide format in a ST4 manner

Seems to me that the mount isn't reacting to the guide pulses, which should have flagged up in calibration ... I've no idea or interest in the air .. it only uses part of the PhD software and seems to have its own figures which are far lower than within the phd2 software

How can you have it start guiding in the .10 region but can't complete a 2 min sub? The mount and your 72 should be able to easily do that unguided.. 

I'd cut out the air and use it directly with PhD, read how to set it up and properly calibrate.. key to good guiding is careful PA doesn't make PhD work so hard, good balance and careful calibration.. 

[michael8554]

I can only see a red Dec line in the graph.

If this means that the Red and blue graphs are superimposed, that points to an orthogonality error in the Cal, or poor PA.

In the second image, the main and multistar boxes have moved off the stars, but the Guide Star window is still showing a good star is selected.

Best to post the GuideLog.

Michael

 

[Iem1]

Thank you for all the replies folks.

I'm taking note of the things being suggested. I will head to an area with service tonight so I can research specific things and report back here with any issues.

I will go the extra mile with the PA too and test it independently of the guiding. I know unguided, with good PA I can manage 2 minute subs, I have done it before with drfit alignment via the handcontroller.

One thing I am querying is my DEC balance. The dove tail of my Z73 is short, too short to balance the DEC without having to shimmy the scope up to the end of the EQ6's clamp. So it is only being held by one of the grips instead of two. It's not massively unbalanced, but definitely not ideal. I chose safety of the rig over perfect balance atm. Need to get that sorted ASAP so both grips hold the bar AND i can balance it properly. Could also be not helping.

Although, I am pretty confident I'm messing something up in the settings/calibration step. Looking forward to getting back out there!

[Iem1]

Just doing some reading;

Would the default calibration step duration of 2000 ms need to be increased? Read something that suggested 8000-10000 ms for the ZWO's mini scope FL?

Think it was for the calibration step the post mentioned, but could be the RA and/or DEC

I left all of mine as default;

[michael8554]

You have Auto Restore Calibration selected.

So next time you set up, ASIAir will use an old Calibration and go straight into guiding.

Which is fine if you have a permanently setup on a fixed pier......

Michael

 

[AstroNebulee]

2 hours ago, Iem1 said:

Just doing some reading;

Would the default calibration step duration of 2000 ms need to be increased? Read something that suggested 8000-10000 ms for the ZWO's mini scope FL?

Think it was for the calibration step the post mentioned, but could be the RA and/or DEC

I left all of mine as default;

I have zwo mini guidescope and zwo asi120mc-s as my guidecamera and theses settings work for me. 

Lee

[newbie alert]

Also if you use phd2 directly you can run the guiding assistant.. not sure that you have that with the air, something tells me it's missing

[Iem1]

Second night completed, and I discovered a method that really improved my guiding I think...turning the guiding on.

After figuring that out, there was no 10-20 seconds of accuracy before the upwards spiral.

as an average I would say i was achieving;

RA ~ 0.75"

Dec ~ 0.35" 

My PA

Guiding

3 minute sub of the Cygnus Wall 

Are these values within the realms of what is to be expected for my set up? ( RA ~0.75 & Dec ~ 0.35)

Also, I think I might need to adjust my dithering intervals. It was set to a 60 second 'wait' during the dither, but the figures for guiding did not show as settled (back to the average 0.75 etc) until well into the next 3 minute exposure. I'm not sure how "live" the feedback is, but if it's pretty spot on then half my exposure time has been with high values for RA Dec due to the disturbance caused by dithering.

I will post one of the actual subs from my laptop in the morning for closer inspection.

Any tips/feedback are most welcome as always, cheers guys. Appreciate the guidance (pun intended).

[AstroNebulee]

That's great you got it working better now. One thing you could bring down the RA and dec aggression a bit that would hopefully smooth out the lines on the graph and be less saw toothed. 

Where is the dither wait setting to, I can't see it on my asiair pro. 

I set the dither 2 pixels every frame and have a guide stability of 4" for 3secs, and this works on my mount great (AzGti) but you could go lower that 4"easily with your mount. I know it should be lower but I'd struggle on my mount not meant for astrophotography. This is what works for me and get good results but your settings will differ slightly for your mount. 

Lee 

 

[Simon Pepper]

4 hours ago, Iem1 said:

Second night completed, and I discovered a method that really improved my guiding I think...turning the guiding on.

After figuring that out, there was no 10-20 seconds of accuracy before the upwards spiral.

as an average I would say i was achieving;

RA ~ 0.75"

Dec ~ 0.35" 

My PA

Guiding

3 minute sub of the Cygnus Wall 

Are these values within the realms of what is to be expected for my set up? ( RA ~0.75 & Dec ~ 0.35)

Also, I think I might need to adjust my dithering intervals. It was set to a 60 second 'wait' during the dither, but the figures for guiding did not show as settled (back to the average 0.75 etc) until well into the next 3 minute exposure. I'm not sure how "live" the feedback is, but if it's pretty spot on then half my exposure time has been with high values for RA Dec due to the disturbance caused by dithering.

I will post one of the actual subs from my laptop in the morning for closer inspection.

Any tips/feedback are most welcome as always, cheers guys. Appreciate the guidance (pun intended).

Now that’s a PA! Also my best guiding ever that I saw anyway was 0.56 so you one up already! Glad your sorted it!

[Iem1]

6 hours ago, AstroNebulee said:

That's great you got it working better now. One thing you could bring down the RA and dec aggression a bit that would hopefully smooth out the lines on the graph and be less saw toothed. 

Where is the dither wait setting to, I can't see it on my asiair pro. 

I set the dither 2 pixels every frame and have a guide stability of 4" for 3secs, and this works on my mount great (AzGti) but you could go lower that 4"easily with your mount. I know it should be lower but I'd struggle on my mount not meant for astrophotography. This is what works for me and get good results but your settings will differ slightly for your mount. 

Lee 

 

Thank you for info, I forgot to return aggr to a lower setting after I was tinkering with it on the first outing.

I think I might have misunderstood the Timeout setting I thought that was time waited after dithering! Mine was set to 60s originally but moved it to 120s thinking it was increasing the time it allowed the guiding to settle back down!

Is it normal for the guiding to still be disturbed by the dither (or at least appear to be) well into the next exposure being taken? About halfway through the next 3 minutes image the numbers would begun to stabilise.

Here was my dither settings screen;

4 hours ago, Simon Pepper said:

Now that’s a PA! Also my best guiding ever that I saw anyway was 0.56 so you one up already! Glad your sorted it!

Thank you, it took me about 30 minutes of going 'Too far past it and back again' to achieve before I finally gave up on improving it

it was uncommon to go below 0.70 RA, but DEC was pretty stable around 0.35 - 0.40

[Iem1]

Here is what a 3 minute sub looked like straight from the camera:

I think it looks ok in respect to guiding etc ..Though it looks a touch soft. Not sure if Dew or (more likely) my focusing.

Edited August 8, 2022 by Iem1