Getting the best performance from my AM5: Page 29

Getting the best performance from my AM5

MarcK

Lain402
Don't dash my hopes that this company will act a little more intelligently 😅
It would really be so easy to learn from the users and work together towards a common goal ✨✨✨

Lain402

MarcK
You mean … easy as 1,2,3 ? 😂
If you have some time to browse through this forum you’ll see that the whole place is a testament of what ZWO is capable in terms of customer service. It’s not brilliant, to say the least.

Here you’ll find some users with VERY high level of knowledge in astrophotography, electronic engineering, coding and computer engineering in general ( don't count me in, I’m just an ignorant person).

When you have a so strong base of users who are so dedicated (passionate ! ) about the products you are making money from and you can’t listen to what they say … that’s a waste you can’t afford for ever.

As I said before, it’s not that they can’t hear, but more a lack of basic understanding of how their own products works. Just see how many times they reply complete nonsense in the comments, before disappearing for weeks…

Galaxium

w7ay

I took my ZWO provided PE graph and digitized it via WebPlotDigitizer. I took that data and put it in a spreadsheet and calculated the local slope between each row of data. That didn't work out so well but I was able to visually identify the max slop area and choose the points to give me my maximum slope.

I chose these points to calculate my max slope:

(250.92, 6.588)
(251.03, 2.5158)

=> 4.0722 / ( 0.11 * (24 hr * 3600 sec / 360 degrees )
=> 4.0722 / (0.11 * 240)

I am unsure about the 240 as it relates to my AM5. Graph below of a November 2023 mount.

Max Slope (arc-sec / sec) = 0.154

Am I doing this correctly? My guiding results were not great with the ASIAIR+ defaults. I have been testing RA and DEC Aggression percentages. I have found this thread and everything is making more sense. It appears ZWO has made some improvements to the AM5 mounts over time? My graph below for inquiring minds.

I have not read how to properly calculate the "Calibration Step" size. Can someone clear this up for me? Kevin_A

ASIAIR+
William Optics 32mm f/3.75 Guidescope Focal Length 120mm
ASI120MC Mini (I just tossed my ASI 174MM in the garbage which I knew was a mistake but now I know it is confirmed as a mistake)
AM5
Redcat 71
I assume 0.5x sidereal since I haven't changed anything in my ASIAAIR+.

Many thanks to everyone in this thread with special appreciate to Chen. Thank you!

Kevin_A

Galaxium first of all do not use a color camera to guide with as it will not work very well. Just get yourself a 120mm mini. Calibration steps for that setup is anywhere between 1800ms to 2000ms it is not that critical with a 120mm guide scope. It is solely based on the guide scope focal length and pixel size. Phd2 has an advanced tab under guiding you can use to verify for yourself.
My mount has a slope of 0.155arcsec/sec and your setting could be similar…. But not definitely the same as the slope may be worse in an area that is not in the partial graph.

Galaxium

Kevin_A Thank you for responding, Kevin.

I had a typo in that post. My guide camera is a ASI120MM Mini. It is sitting on my desk now waiting for tonight.

I have read your past posts that reference focal length of the guide scope and pixel size of the guide camera being the two factors that dictate the Calibration Step. When you make ballpark calls for people like you just did for me, is this using lots of experience with Phd2 or is there some formula I should be using to get a good sense of where I need to be?

Kevin_A

Galaxium it is a calculation to move the guide star at least 25 pixels in about 10-14 steps.
Like I said this formula can be found on the web and it is also in the phd2 software…. So not my doing… it is a calculation based on your inputs. Bigger guide scopes and OAG are usually between 300-600ms and the typical 120mm guide scope with 120 guide cam is around 1800-2000ms. My 240mm scope with a 120mm mini is around 900ms. Bigger the guide scope FL the smaller the calibration ms size.

Galaxium

Just making a few small changes from this thread and my Total Error is down to under 0.7". I would have never thought this possible. I am going to keep working on this. Thank you Chen, Kevin, and everyone for contributing. I also asked ZWO for a CSV file of all data points from 0 - 360. I am sure they will ignore this request, but I wanted to give it a try.

Galaxium

w7ay

This is just about the math Chen. I would appreciate some guidance on this from anyone here.

Regarding #3.

My slope was 0.15 or 15 arc-sec/sec. I assume to get the Max RA duration I would do the following:

Max RA = (2 * 15 ) / 0.5
Max RA = 60

Is this correct?

Gagan

Last night, after two months between cloudy weather and work commitments, I managed to finally setup the mount and give it a go.

I set it up on a Pier with PE200, and used a 2600MC coupled with 135mm Samyang @ F/2.8, guided with the 462MC on a ZWO F4 guidescope. The control is performed by a Mele Mini Pc with PHD2 for guiding and APT for main camera control.

Everything was polar aligned using the sharpcap routine.

For some reason it started the night really well, at around 0.32” total RMS, and even reaching 0.28”. This was with the main lens pointing almost vertically to the zenith because my target (Spaghetti Nebula) was close to the meridian already.

Then the mount stopped tracking because it reached the limits.

I performed a manual meridian flip, recalibrated PHD2 guiding and couldn’t seem to make it work anymore, it wasn’t able to go lower than 0.9” with peaks and moments reaching 1.6”.

I tried changing a bunch of setting but nothing helped.

I attach an image of the guiding, hoping someone is able to help me out here, because I have no idea, about what is wrong..

Thanks

The Setup

The PHD2 Guiding

Kevin_A

Gagan yeah, mine did not like to guide on the other side of the meridian last night too. The main guide star looks a bit too wide so that might not help. I sometimes look at the main guide star and if it is not good I restart guiding again so it picks a new star. You could be running into a bit of bad atmosphere too as the skies are a bit turbulent. I also find that the counterweight might be an issue when you run a light scope like a Rokinon 135, so I don’t use it for my 135 f2 setup. I found guiding at 0.5s better last night than my usual 1s.

Gagan

Kevin_A
Hey Kevin, thanks a lot for taking the time to share your info.

I will definitely have to give it another try and maybe without the counterweight.

I initial thought that adding just a 1kg counterweight would help with the guiding, as it should make the mount more stable.

I understand, from all your help and answers on this forum, that you know your way around the AM5 and the harmonic mounts in general as Chen also does.

If you allow me, I would like unfortunately to bother a little more 🙂 and ask a tiny bit more for help..

I have calculated the slope based on my chart, by using the steepest slope that Chen suggests according to my graph (even if is possible that is not the steepest, as it might not be represented in the chart by ZWO).

I mainly have 2 questions:

Is there a way to measure the full PE curve of my mount, maybe with PHD2 guiding, and how long would it take to complete a full turn (for a 288 seconds period mount) ?
And once I have the slope, where do I go from there? Meaning how do I select the settings from the guiding (Aggression, MnMo, MaxRA/MaxDEC) ?

Thanks again.

And of course if anybody else has any suggestions and advice you are more than welcome to add them !

I will be happy to try anything to make sure that I get some repeatable setting and guiding.

Clear Skies !

Gagan

Kevin_A

Gagan you need to run the mount with guiding turned off in phd2. You need to run at least double the period of the mount and even 4 times will verify accuracy. Make sure polar alignment is good first. Once you have that data you can see where the worst slope is.

Gagan

Kevin_A I will give it a go when I have a moment !

Thanks again !

Convair

Hi everyone! I am new with AM5 and I found your discussion about guiding numbers very instructive, but still I have difficulty to fully understand these settings. So, can you please suggest me how should I set my guiding numbers, considering my mount PE test report graphic? I am using two different scopes, a SkyWatcher 200/1000 PDS and an Askar 300 (60/300mm), and a 50mm guide scope with ASI120 MC-S as guiding camera. I used mostly the standard numbers in the beginning but unfortunately, after the last ASIAIR firmware update, I failed to guide anymore. I struggle a while but still no more consistent guiding. Thank you in advance!

Kevin_A

Convair firstly…. Use a mono guide camera not a colour one. Next set your calibration step size to about 1350ms, durations to about 450ms on Ra and Dec using either 0.5s or 1s guide exposures. Try 1s first as you get better guide star SNR with that longer exposure. The camera gain needs to be high enough that multistar guiding uses and finds more than 8 guide stars, 12 preferably. Make sure the guide scope is well focussed and calibrate in the south near the meridian on the side you plan on imaging. I would upgrade your guide camera to either the 120mm mini or the 220mm mini. Your PE graph is quite good so it should be easily guided. Minmo should be set to 0.1px not 0.2px under the advanced tab, they call it trigger accuracy but it is really Minmo… I think it may be in the advanced tab under mount tab . Cheers!

Convair

Kevin_A man, thank you! I´ll give it a try. I use to guide very smooth before ASIAIR last update, after that is almost a disaster. I really fight to have back my old guiding.

Scotty

Maybe someone can give some advice. I've had the AM5 for a year and its been fine with my wide field scopes (mainly Sharpstar 94EDPH) at 420mm FL. Back in March I added a Skywatcher Esprit 120ED (860mm FL) as the main scope (using Evoguide 50ED and ASI290MM mini as guider) using the 200mm Pier and HEQ5 tripod. I have had more variable guiding but have been able to shoot up to 300s subs and get several very nice images. Pointing at targets high in the sky yeilded worse guding but acceptable. Past couple of sessions though have had issues with an inability to even shoot 60s subs with guiding on at high targets. 8 out of 10 subs are unusable with sharp oscillations causing spikes or double stars. I thought at first it might be seeing related but the second session had good seeing conditions. No amount of playing with agression helps or recalibration on the target or calibrating South near the equator. Turning guiding off however yeilds pinpoint stars at 60s exp. As such I'm at a loss as the mount is clearly PAed OK and tracking OK but the guiding algorithm seems to be sending it haywire when it should be issuing very few corrections. I've tried my ASI120MM mini as well with no change in outcome. Also played with max Dec/RA durations between 350 and 1000 (normally I have Dec at 350 and RA at 500). Have tried 0.5s, 1s and 2s guide exp (normally use 1s) and no change. Agression between 25% and 50% no impact. Last session I ended up turning guiding on to get a Dither, then switched it off and shot unguided before rinse and repeat. Painful but at least I got useable luminance data. The weight of the scope fully loaded is 14kg so I have a 4.5kg CW and the ASIAIR Plus is running 2.1.1 (10.74). I have also found the centre of gravity of the scope and line this up with the middle of saddle. Everything is tight including the guidescope. I haven't upgraded the ASIAIR and not sure whether there is anything advantageous to doing so? I'm taking heart that the mount tracks well unguided....still any suggestions welcome as the images from the Esprit are beautiful but I need consistency from the guiding on the AM5.

Kevin_A

Scotty you need to update to the latest version of asiair 2.1.2 then go into the guiding advanced tab and make sure the trigger accuracy is set at 0.1px and not 0.2px. That trigger accuracy is Minmo.

Scotty

Kevin_A ok Kevin - will give it a go. Many thanks.

Scotty

Kevin_A Hi Kevin - just to report back that after the upgrade the AM5 has been very good with the Esprit 120ED over the couple of sessions that the clouds have parted. Thanks kindly.

wookash

hi All, I've posted this separately, but this thread is much more popular, so re-posting here, too..

I’ve bought am3 and was able to test once on a windy night with 2h clear window. I also forgot to secure the latitude adjustment locks but still excluding big spikes at the beginning and end of session I got around 1” RMS. The load is c.a. 4.5 kg (mak127 plus 189fl 50mm guide scope).

I’ve been reading posts about periodic error and started drawing lines on my report and calculated steepest slope error at c.a. 0.22 arcsec/sec. I’m attaching my report - I’m worried about the spikes on the graph - should I be?

Kevin_A

wookash your graph looks good and typical and nothing to worry about!

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