RA Spikes

[a.ne...@gmail.com]

Hi All,

Hoping for a bit of guidance here. I've been maintaining decent guiding over the last couple months, however I've not yet successfully been able to maintain a total error of less that 1 arc second. My DEC is very solid, barely deviates from the axis. However, I've consistently been experiencing RA spikes and instability. My stars are ok, but you can tell they are mildly fuzzy and not quite perfect circles.

At first I thought my polar alignment may need some work, so I installed sharpcap and have been using the polar align tool. What I thought was excellent polar alignment was only "fair". Since using sharpcap, I'm confident my polar alignment has been spot on.

Still RA spikes and alot of variability. I have spent nights fiddling with settings, trying to be as methodical as I can be. I did eventually bring these spikes down into better levels, however I was still seeing a fair amount of error (1.5" error on RA give or take).

The other night, I opted to go for a completely new equipment profile, and the key difference here is I adjusted the sidereal rates in eqmod to x.9 as opposed to x.5 before.

Still seeing a large amount of RA spikes, although I will say that these spikes seem much more rhythmic and consistent.

My mount is a HEQ5 Pro, ASI120 mini, and WO 50mm guidescope. 

I've included my guide log from this most recent session, and I'm looking for any guidance on what to try first and which direction I take my settings in a methodical and meaningful way to help reign in the RA guiding.

https://openphdguiding.org/logs/dl/PHD2_logs_ywzz.zip

Thanks for your time.

Andrew

 

[Brian Valente]

Hi Andrew

Something is up with your mount's RA. you have a fairly significant and repeating error.

Looking at your unguided GA run (so no guide pulses at all) you can see it clearly (gree is my marks showing the period):

examining the frequency analysis you can see it plainly as a 13.5s fairly large (for the frequency) amplitude error:

PHD is unable to correct for these large and fast mount changes, and that's what you are seeing in your guiding. In fact, it seems like guiding is compounding the issue

here's the short bit of guiding that shows the amplitude is now 3.7" when guiding, not good

I'm not sure what is causing this but it's something in the mount - you may check with the user group, or contact ioptron and show them the unguided results above. 

You may also doublecheck that there isn't any sort of periodic error correction or some sort of compensation enabled in the mount or EQmod

Brian

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/783f2b91-3006-489d-96d6-ad7ac482b9c3n%40googlegroups.com.

--

Brian 

Brian Valente

portfolio brianvalentephotography.com 

[Andrew Nerness]

Thanks Brian,

I’ve sent a note to skywatcher’s support team to see if they can help pinpoint the issue. I’ll also post on a general form to see if there are any setting that may be off in eqmod. Will update as I learn more.

Best,

Andrew 

Sent from my iPhone

On Oct 6, 2020, at 9:19 PM, Brian Valente <bval...@gmail.com> wrote:



Hi Andrew

Something is up with your mount's RA. you have a fairly significant and repeating error.

Looking at your unguided GA run (so no guide pulses at all) you can see it clearly (gree is my marks showing the period):

<image.png>

examining the frequency analysis you can see it plainly as a 13.5s fairly large (for the frequency) amplitude error:

<image.png>

PHD is unable to correct for these large and fast mount changes, and that's what you are seeing in your guiding. In fact, it seems like guiding is compounding the issue

<image.png>

here's the short bit of guiding that shows the amplitude is now 3.7" when guiding, not good

You received this message because you are subscribed to a topic in the Google Groups "Open PHD Guiding" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/open-phd-guiding/cgjM-fd-YRQ/unsubscribe.
To unsubscribe from this group and all its topics, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i5tgpMT8AACC%3D4Hc4DkX3h%2BR4bFoSiMevxVU7ZskOVPSg%40mail.gmail.com.

[Jynn Freeman]

Looks like yet another victim of HEQ5 Pro’s gear mesh issue. It’s getting more frequent than ever.

Simply put, try adjust the RA gears’ positioning, make them contact more without binding.

While it sounds easy, it’s actually a pretty hard job...

FEEL TRUE POWER

在 2020年10月7日，上午10:19，Brian Valente <bval...@gmail.com> 写道：



Hi Andrew

Something is up with your mount's RA. you have a fairly significant and repeating error.

Looking at your unguided GA run (so no guide pulses at all) you can see it clearly (gree is my marks showing the period):

<image.png>

examining the frequency analysis you can see it plainly as a 13.5s fairly large (for the frequency) amplitude error:

<image.png>

PHD is unable to correct for these large and fast mount changes, and that's what you are seeing in your guiding. In fact, it seems like guiding is compounding the issue

<image.png>

here's the short bit of guiding that shows the amplitude is now 3.7" when guiding, not good

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i5tgpMT8AACC%3D4Hc4DkX3h%2BR4bFoSiMevxVU7ZskOVPSg%40mail.gmail.com.

[Andrew Nerness]

Thanks Jynn,

I’ve also thought about going with the belt mod for the mount. Although, I’ve heard hit or miss results and some lofty expectations vs. what is actually achieved. 

Tried again last night doing several different calibrations and my RA was still all over the place.

A bit disappointing for what I paid for the mount and how new it is. 

 Anything in particular I should look for if I do open up the mount and check the gears? 

I’ve reached out to skywatcher support but have not heard anything back yet. 

Andrew

On Oct 9, 2020, at 3:19 PM, Jynn Freeman <fma...@live.cn> wrote:



You received this message because you are subscribed to a topic in the Google Groups "Open PHD Guiding" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/open-phd-guiding/cgjM-fd-YRQ/unsubscribe.
To unsubscribe from this group and all its topics, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/HK0PR01MB2209651352777A470568CCE2C40A0%40HK0PR01MB2209.apcprd01.prod.exchangelabs.com.

[Jynn Freeman]

Hi Andrew

Trust me ive experienced all the pains that you've experienced so far, and even more...

I’ve been tackling with my mounts RA spike issue for weeks now. Didn’t achieve any good results at all. I tried to tune my gears, to make them mesh with each other, however the spikes would always return. 

I’ve seen quite a few other HEQ5 owners having the same issue. Problem is, Sky-Watcher don’t cover preciseness in their consumer support. Which means you won’t be able to get a fix for free just because you have a bad tracking performance.

There are two things that we can do for now,

1. Go belt mod. It’s the only cure to 13.6s RA spikes. Though you still have to make your belts tightened with tension. However if you have the spikes from beginning, there’s a very little chance for you to fix it by simply adjusting your gear mesh. There might be something faulty on your gears and Sky-Watcher won’t fix that for you, you can only count on a return policy from the retailer, or go belt mod instead. Belt mod replaces all the gears in your gearbox, and the 13.6s RA spikes issue is tangled with those metal gears. Thus the mod has a large chance to fix the problem for you if you have installed it correctly, by replacing those faulty gears.

2. Avoid buying any other Sky-Watcher mounts from now ;) I’m super pissed by Sky-Watcher’s terrible customer support. I’m pretty sure that my next mount wouldn’t be a Sky-Watcher mount at all.

My belt mod is still stuck in local custody, wish me luck ;) would report back if I got rid of my spikes with the belt mod.

Sincerely,

Jynn Freeman

在 2020年10月10日，上午5:41，Andrew Nerness <a.ne...@gmail.com> 写道：

 Thanks Jynn,

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/7DC1E582-3F06-4ACA-846E-DC8E33ACC102%40gmail.com.

[Andrew Nerness]

Thanks Jynn,

I’m most interested in whether you find a meaningful difference with the belt mod. Keep me posted please.

In the meantime I intend to play with the motors and gearing to try and achieve the best results I can in the meantime.

I second your thoughts on frustrations with Skywatchers customer support, it is a shame. 

Sent from my iPhone

On Oct 13, 2020, at 10:50 PM, Jynn Freeman <fma...@live.cn> wrote:

 Hi Andrew

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/HK0PR01MB22094EB9D2BA5A9AF25E9F58C4080%40HK0PR01MB2209.apcprd01.prod.exchangelabs.com.

[Jynn Freeman]

Tweak the angles or relationships of those gears, instead of just distance. Simply tweaking the distance wouldn’t help. If you’re lucky enough you might find a special angle that can help you to kill those spikes. However you need to do this in a starry night with the guiding working, which is extra hard.

Best luck to you,

Freeman

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/413D37B5-60A8-47AD-8EFF-8358866007E6%40gmail.com.

[Andrew Nerness]

Thank you. 

On this point - if I manipulate the gearing after I’ve calibrated the mount, I assume it’s prudent to recalibrate the guiding each time?

Or do I want to keep the same calibration and manipulate the the gearing to see if it alleviates the RA spikes on the existing calibration?

Want to make sure I’m making methodical changes to see if there is any improvement. 

Sent from my iPhone

On Oct 14, 2020, at 3:18 PM, Jynn Freeman <fma...@live.cn> wrote:

 Tweak the angles or relationships of those gears, instead of just distance. Simply tweaking the distance wouldn’t help. If you’re lucky enough you might find a special angle that can help you to kill those spikes. However you need to do this in a starry night with the guiding working, which is extra hard.

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/HK0PR01MB25946EAE43E87506E6D4E851C4050%40HK0PR01MB2594.apcprd01.prod.exchangelabs.com.

[Jynn Freeman]

You should be seeing improvements immediately after you get the right angle. However it’s better to stop guiding ( or make it really insensitive ) before you start tuning. A good way is to start the “guiding assistant” which can both keep the monitoring and prevent guiding. Then you can do gears tuning. You might also want to scale out the guiding graph to +- 16’’ so that you won’t get lost easily.

 

Once if you see the rapid sharp spikes are gone, tighten up the screws and recalibrate guiding again.

 

This can be very frustrating, but I hope you all the good luck!

 

Freeman

 

发送自 Windows 10 版邮件应用

 

---

发件人: open-phd...@googlegroups.com <open-phd...@googlegroups.com> 代表 Andrew Nerness <a.ne...@gmail.com>
发送时间: Thursday, October 15, 2020 8:06:29 AM
收件人: open-phd...@googlegroups.com <open-phd...@googlegroups.com>
主题: Re: [open-phd-guiding] RA Spikes

 

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/2FC61681-574D-4B7E-B7C6-A2D9DD6C557B%40gmail.com.

[Andrew Nerness]

Very helpful - thank you very much!

Sent from my iPhone

On Oct 14, 2020, at 7:22 PM, Jynn Freeman <fma...@live.cn> wrote:



To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/HK0PR01MB2594D9F7CF314EA054996AD6C4020%40HK0PR01MB2594.apcprd01.prod.exchangelabs.com.