ASIAir- guiding seems worse every time I shoot

[Anthony Quintile]

To the best of my knowledge, these are my guide logs moved from the ASIAir Micro SD card to my PHD2 log file on my PC. (File dates/names were weird, seemed to imply that they were created in 2016, which is impossible, I am not sure why.)

https://openphdguiding.org/logs/dl/PHD2_logs_Rii6.zip

The first time I used the ASIAir was among the best guiding results I have had, (from a guiding perspective. I was having some sort of flexure issue that was resolved with help from this forum.)

Those results were consistent and around .75" total RMS, maybe less.Since then, every time I use the ASIAir, or PHD2, it seems like the guiding is slightly worse than the last.Tonight, my guess is that on the average the total RMS was about 1.10". Guiding seems to never really settle down, and sometimes spikes into around 1.60"+ total rms.

I am using a Losmandy G11 Gemini 2, and either a 280mm ZWO scope or and OAG on a Celestron 8SE at 1180mm, (I know that's weird, I'll explain if need be), with an ASI120mm Mini camera.

The Losmandy has the spring loaded worm drives.

Although I have heard that with this mount, with the springs, I should balance both axes, I have also heard that the mount should be east heavy. I unbalanced the RA tonight part way through, and that seemed to maybe have helped the RA? I weighted the Dec slightly off with no difference. (Recently I have been shooting with a relatively lightweight refractor, so I am no where near the capacity of this mount.)

After repeated earlier confirmations, my polar align routine with the Polemaster seems to be really good. (Also, I have heard maybe that polar align should be slightly off, I am assuming on the AZ axis, to help with guiding, but I am not doing that. I sorta half-assed tried that towards the end of this evening, but no real change in outcome.)

I'd like to be able to use the ASIAir with my mount rather than my lap top for many reasons, and I think others have had significantly better results than this with this device. I also think that the Losmandy mount ought to perform better than this as well. The limited-feature version of PHD2 on the ASIAir lacks some of the flexibility and buiilt-in assistance that the full program has, so maybe I am stuck with using my laptop? But then, why did I have good results at first?

I am very new to all of this, any help is much appreciated.

[Brian Valente]

Hi Anthony

 

Good to hear from you again

 

You covered a couple different topics,

 

>>> Although I have heard that with this mount, with the springs, I should balance both axes, I have also heard that the mount should be east heavy. I unbalanced the RA tonight part way through, and that seemed to maybe have helped the RA?

 

With spring-loaded worms, you should balance both axis. It won’t make that much difference if you slightly unbalance it, but you’ll introduce another variable when you don’t have to, particularly when switching to opposite side of pier

 

 

 

>>> Those results were consistent and around .75" total RMS, maybe less.Since then, every time I use the ASIAir, or PHD2, it seems like the guiding is slightly worse than the last.Tonight, my guess is that on the average the total RMS was about 1.10". Guiding seems to never really settle down, and sometimes spikes into around 1.60"+ total rms.

 

Looking at the longest run of 2 hours on 11-03-101650, your total RMS over that period was 1.16” or about 0.42px. RA and DEC are fairly close, the scatterplot looks nice and round.

 

I think the performance you are observing is the limitations of your seeing, and less about the mount performance. There are a few things you can try to tune up your setup (see below)

 

A total RMS Of 0.77” would roughly be 0.28 px – less than ¼ pixel difference. That is generally the range where seeing variations would make sense, particularly given your solid metrics otherwise

 

Some things you can do to try and improve performance:

 

Turn on dec backlash

Turn up your DEC aggression

Try running PEC via PEMPro (they have a free trial) to reduce your RA error. Once you do that, you can combine with  the short guide exposure and PPEC algorithm to address your 31sec PE.

 

 

 

 

>>>. I also think that the Losmandy mount ought to perform better than this as well

 

How do you think it should perform?

 

Your results from this guiding session should produce nice round stars, and as I mentioned before the small differences in guiding are likely due to seeing conditions.

 

The mount responds to your guiding well, and you are generally around 1” RMS. Seems to me like your mount is doing fine. Not sure why you continue to point to your mount as the source of your problems, but maybe I’m missing something here.

 

 

Thanks

 

Brian

 

portfolio https://www.brianvalentephotography.com/

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[Anthony Quintile]

I think your advice on setting up PEC is pretty good, especially if I want to use the ASIAir which does not, (I think?), have the PEC algorithm that the full version does. I read here about that the other day. I am still unclear as to how to train that using the various tools, but I can research that and figure it out I am sure.

My comment about the mount was meant to be a statement that the mount shouldn't be the issue. I see other people claim "20 minute unguided subs" and ".35" total rms" with this mount, and I am not even in the ball park on that. So I am asking, "so then, what should I change in my PHD settings or balance, or whatever...". I think these statements are driving my concern, and maybe those results are the result of people bragging, embellishing, and aren't even really relevant to the quality of my photos anyway?

I had adjusted aggressiveness on both RA and Dec and it seemed to have little effect until I reduced those to only 10%, (which was bad). I had them at 70%, went as high as 90%, and played around between 40% and 70%. It didn't really seem to change anything dramatically. I also used exposures between 1 and 3 seconds, but 1 second seemed to be the best.

I swear that the biggest change was when I took off some counter shaft weight and weighted the mount east heavy. That dropped my RA RMS to as low as .60"ish and it had been running at over 1.00".

You state that the results I am getting are because of seeing, which makes sense since it varies night to night with the same set up. I guess my photos won't be too good on those nights because of seeing on its own anyway, so guiding is only compounding an otherwise less than ideal situation. It would figure that the year I choose to get back into astrophotography delivers the worst winter weather in a decade. I think our clear nights here in Flagstaff are plagued by the jet stream pushing in the next front.

On turning on Dec backlash, the Losmandy instructions specifically say to turn off the backlash settings by making the "TVC" equal to 0. I will try turning that on if you think it will help, but it is counter to specific advice from Losmandy. Do you know what I would set that to then?

I'll try the other things you mention as well. Thanks for your help Brian!

[Brian Valente]

Hi Anthony

the losmandy instructions are correct - you want to turn off backlash compensation IN the mount. 

but you want to turn on backlash compensation in PHD (the reason you turn it off in the mount is so it doesn't fight with PHD's settings). on the spring-loaded worm my suggestion is to turn it on and set it around 800ms and let the auto backlash compensation adjust it from there. The 'measure backlash' test in the guiding assistant may report it can't measure backlash, so what i suggested is a good place to start

regarding PEC, you set it up and load it into the mount, so it's always there. PEMPro is imho the best way to measure and record PE for correction. I think it's possible with other approaches such as using PHD corrections, but personally i find PEMPro to be much better (full disclosure I have no relationship with PEMPro at all).

as for 0.3" guiding and all that, i've been able to achieve those levels too, and i'm in urban los angeles bortle 9. terrible skies! but with the right conditions, even then i can pull it off and you might as well. but regular consistent guiding at that level really requires some exceptional seeing conditions

hth

Brian

--

Brian 

Brian Valente

portfolio brianvalentephotography.com 

[Anthony Quintile]

Brian-

 

I’ll need to poke around in the app some more, but I don’t think the ASIAir has a setting for Dec backlash. ZWO loaded a dumbed-down version of PHD2 into the device, and I may just need to deal with what it outputs if I am using it rather than my laptop.

 

I may mention to ZWO that they should add in more of the PHD functionality. I can’t see why they wouldn’t except that maybe some of the algorithms are too much for the Raspberry Pi to handle efficiently? I am not a computer programmer, so I really don’t know.

 

I understand what PEC is, I am just afraid of dealing with it. I’ll just have to toughen up and deal.

 

It is good to know that seeing has such a substantial effect on guiding. Thanks for that info!

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[Brian Valente]

ah - yeah i understand now about ASIAir not being a full version of PHD. although dec backlash compensation has been available for quite some time (under brain-> algorithms under the DEC settings) so you may doublecheck to see if it's available to you

PEC is kinda scary but not too hard once you get the idea. You seem like a logical detail-oriented person, i'm sure it will be fine and Ray (author of PEMPro) is good with help there

Brian

[Brian Valente]

Anthony i just looked at ASIAir's user manual. it is really stripped down, and I don't see the option for backlash compensation, so sorry I may have lead you down the wrong path for that software setup

Reflecting on your past comments and desire for exceptional results, i'm not sure that product would be up to meeting your standards

If you like the idea and form factor you might consider rolling your own by getting an Intel NUC and loading it with standard versions. I do this with PHD2, sequence generator pro, PEMPro, etc. and it all sits on my telescope. it's not cheap, but it's a next level kind of thing for something like ASIAir

Brian

[Anthony Quintile]

I am OK with getting the best possible results for this platform, sometimes. (With my small refractor @ 430mm and 1.87”/px resolution, not my SCT 1360mm at .59”/px, (I know, not actually that good), for example…)

What had me concerned was the disparity between earlier results (+/- .75 total rms) and the past couple of nights.

You have me convinced that seeing is the culprit for the most part.

 

I will probably upgrade to a NUC or something eventually, but I have a lot more learning to do on other fronts before I spend that $.

 

Thanks!

[Brian Valente]

Sounds like a good plan. 

I'm only guessing it's seeing, as I can't really see anything else but keep a watch over the next few sessions. 

Tuning up your guiding parameters and mount with those recommendations may uncover some additional opportunities for improvement, but let's see where it goes

Brian

[bw_msgboard]

Hi guys.  I haven’t heard about this ASIAir product before but it sounds like a hacked version of PHD2 that is being distributed by ZWO.  If that’s the case, we won’t provide support for it on this forum.  We only support the PHD2 releases that come from the OpenPHDGuiding.org web site.  So if you need help or advice on using this thing, I think you’ll need to ask on some other forum – perhaps a ZWO support forum or a group specific to your mount.

 

Sorry,

Bruce

 

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[Anthony Quintile]

Bruce-

 

That’s interesting to know that you guys didn’t help with it. I had assumed some level of involvement, but I guess I was wrong.

[bw_msgboard]

No, it looks like they helped themselves to the open source code, hacked it, and embedded it in a commercial product.  Nice.

 

Bruce

 

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[Anthony Quintile]

Now I feel kinda bad about buying it…

[bw_msgboard]

No worries, Anthony, how could you have known.  If you do get back to a situation where you’re running the real PHD2, we’ll be glad to help you out when needed.

 

Cheers,

[Andy Galasso]

Just to be clear, the PHD2 code is open and freely available for anyone to use, subject to the terms of the source code license that is included with PHD2, or here: https://raw.githubusercontent.com/OpenPHDGuiding/phd2/master/LICENSE.txt

It is explicitly allowed for ZWO to modify the PHD2 code and embed it into the ASIAir, there's no problem with that from a license or code use point of view.

However, since the code is modified, we (PHD2 developers) cannot provide support for the modified version ... that's up to the authors of the modified version (ZWO).

Andy

[Anthony Quintile]

Thanks for the clarification, Andy.

 

 

From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of Andy Galasso
Sent: Tuesday, March 05, 2019 8:20 PM
To: OpenPHD Guiding <open-phd...@googlegroups.com>
Subject: Re: [open-phd-guiding] ASIAir- guiding seems worse every time I shoot

 

Just to be clear, the PHD2 code is open and freely available for anyone to use, subject to the terms of the source code license that is included with PHD2, or here: https://raw.githubusercontent.com/OpenPHDGuiding/phd2/master/LICENSE.txt

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[Jamie Amendolagine]

How about stellarmate? You can buy / download their OS image for a raspberry pi, and it looks like they play nice, or in fact are part of the OSS community. 

On Tuesday, March 5, 2019 at 12:16:55 PM UTC-8, Anthony Quintile wrote:

Now I feel kinda bad about buying it…

 

From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of bw_msgboard
Sent: Tuesday, March 05, 2019 12:40 PM
To: open-phd...@googlegroups.com
Subject: RE: [open-phd-guiding] ASIAir- guiding seems worse every time I shoot

 

No, it looks like they helped themselves to the open source code, hacked it, and embedded it in a commercial product.  Nice.

 

Bruce

 

From: open-phd...@googlegroups.com [mailto:open...@googlegroups.com] On Behalf Of Anthony Quintile
Sent: Tuesday, March 05, 2019 11:29 AM
To: open-phd...@googlegroups.com
Subject: RE: [open-phd-guiding] ASIAir- guiding seems worse every time I shoot

 

Bruce-

 

That’s interesting to know that you guys didn’t help with it. I had assumed some level of involvement, but I guess I was wrong.

 

From: open-phd...@googlegroups.com [mailto:open...@googlegroups.com] On Behalf Of bw_msgboard
Sent: Tuesday, March 05, 2019 12:25 PM
To: open-phd...@googlegroups.com
Subject: RE: [open-phd-guiding] ASIAir- guiding seems worse every time I shoot

 

Hi guys.  I haven’t heard about this ASIAir product before but it sounds like a hacked version of PHD2 that is being distributed by ZWO.  If that’s the case, we won’t provide support for it on this forum.  We only support the PHD2 releases that come from the OpenPHDGuiding.org web site.  So if you need help or advice on using this thing, I think you’ll need to ask on some other forum – perhaps a ZWO support forum or a group specific to your mount.

 

Sorry,

Bruce

 

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Brian 

 

 

 

Brian Valente

portfolio brianvalentephotography.com 

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Brian Valente

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