AM5 Erratic Guiding

SFG8UeX8

Hello, I’ve had my AM5 for about 7 months and suddenly guiding is off the charts. I’ll link the last few guide logs.

Set up:

AM5
ZWO 120mm mini guide cam
Apertura 30mm mini guide scope
ASIAIR
ZWO 533mc
Apertura 60mm refractor
EAF
The last 7 months have been pretty good. RMS at a glance from the AIR was between .5 and .8. Guiding has been so good I don’t pay too much attention to it, but last week on October 22nd something caught my eye after first calibration. Declination went just ran away. This was probably due to poor PA as I had no direct view of Polaris so I had to slew the mount off center to get a clear patch of sky.

Anyways, it seems since then guiding has been way off. I’ve always used default settings (8000ms cal step, 2000ms dec 2000ms Ra pulse) no problems.

I used to run the mount and air off a 3amp power supply but have since switched to a 12v 10amp for the AIR and 12v 5amp for the mount.

I have ensured that everything is tight and there is absolutely no movement on the rig. I’ve also changed calibration step down to 1700ms and dec/ra guide pulses down to 150-700. Sometimes this works great sometimes not.

I have adjusted Aggression up and down. None of it really seems to make a difference. I have been also calibrating within a few degrees of the celestial equator in the quadrant I plan on imaging that night.

Last night I thought was pretty successful with low aggression and low guide pulse (RA15% 150ms/ DEC25%/150). Things were going pretty good so I let it run. Well, I woke up to RA swinging around and RMS around 2.00-3.00. I changed some settings hoping to work through it but no go. Then, I thought maybe the heat coming off my dew heater was affecting guiding so I removed it, nothing changed.

I’ve scoured the forums over the last week reading everything including Chen’s post about the AM5 but nothing seems to stick.

Tonight, I will try mounting just the guide camera and scope to the AM5 just to narrow it down. I also plan using different USB cables for both cameras and also guiding with phd2 to see if there is a problem with the air.

This one is from last night.

phd2-guidelog-2023-11-01-193613.zip

899kB

When I first started seeing issues.

phd2-guidelog-2023-10-22-194723.txt

1MB

A good night from early this year

phd2-guidelog-2023-06-13-213557.txt

2MB

Kevin_A

How many guide stars are you guiding on? Try to get at least 12. Whoever is suggesting and posting 8000ms for calibration step size does not understand guide camera calibration. Haha. 8s is a bad setting but around 1700ms is good. Try upping the gain on your guide camera so you get the most amount of stars possible to guide on with the tiny 120mm guide scope at 1s guide exposures. I use aggressions at between 35-45% with pulses between 350-650ms. Sometimes seeing will be bad and a small guide scope makes guiding hard! Colder weather right now comes with a bit of atmopheric turbulence so stars may be jumping around too.

SFG8UeX8

Thanks, Kevin. I'll give those a try tonight. Yes, I try to aim for 12 stars. I was testing last night, and I think I had the gain down around 53, so there were maybe 6 guide stars. You're right about the stars moving around, so maybe it is seeing. I just can't believe that something might be wrong with the mount. I mean there's not much to go wrong.

Kevin_A

SFG8UeX8 these mounts need really good and big guide scopes in bad skies.
I replaced all my 120mm scopes and 120mm mini guide cams as my results were erratic. I did find that higher gains helped but replacement worked best. I also found that heavier imaging scopes work better than light ones. Strange but true. If you use phd2 lower the Minmo to 0.1 or less and gain 70 or a bit higher if you can.

SFG8UeX8

Last night, I ran PHD2 for 15 minutes using your recommended settings. RA: AGR35, HYS30, MINMO.07. Same for DEC except MINMO .1 and AGR45, 500ms pulse for both. I also ran Guiding Assistant to check DEC backlash (980ms). I know these mounts don't have any, but I had to check it out while I was in there.

After a good run with PHD2, I plugged in the ASI Air Mini to see how it would do and to my surprise, it did very well. Awesome! Then, after maybe 15 minutes, guiding became unstable. Not too bad, total RMS around 1.5, but I figured it would sort itself out and I decided to go to bed. The next morning, I checked my phone and total RMS was around 3-4. Guide logs for the entire night were a mess.

Maybe the ASI Air is the culprit. It seems like it's struggling to produce a constant 1fps to keep up with corrections.

Tonight, I am running NINA and will post guide logs tomorrow night. So far, all is good.

On a side note, I have to say the whole NINA experience so far has been smooth. Plate solving is lightning fast and NINA's 3-star alignment actually works great with my L-Extreme filter in. I usually have to set my guide cam as the main camera because the Air has trouble plate solving with L-Extreme in.

Kevin_A

SFG8UeX8 this mount is super sensitive to guide star quality and the amount of guide stars. It can go to crap easily if the skies and transparency are turbulent and the gain on the guide cam is not enough to get at least 12 stars. The bigger and better the guide scope the better too. Make sure the guiding stars are well defined and I generally stop guiding and let it pick new stars at a few fixed intervals every 2 hours during my run but that is because I use Asiair and it is not as good as Phd2 or others.

SFG8UeX8

I checked in on the Am5 owners' group over on cloudy nights to see anyone has had issues with their mount.
A couple of suggestion were to check Pa, loose connections, mount stability etc... I should mention that my rig despite its current issues guides great at the equator and meridian intersection. I posted some pictures of my success last night over there before checking guide logs. ASI Air can be deceiving at glance when you're looking at guiding from the imaging screen because it only shows 50s timeline.
I just checked guide logs and noticed a couple of times last night RA and DEC were spiking around 7-9.
Something is loose, has to be. how can guiding be so good in the most difficult place to guide and go complete bonkers when pointed at something closer to the poles?
I had said earlier that the main camera was loose, and I was able to get 1/8th of a turn on it. Well...I found that the manual rotator was loose, and the main camera had pretty good amount of play in it. My guide camera sets on top of the main scope, and I think a little play in the main camera is probably causing some movement in the whole OTA.
LOL I'll give her a go tonight and see what happens.

Spikes I was seeing.

AdrianW

I had a similar problem with my guiding but it manifested itself the closer the scope got to the meridian.
I made a few changes all at the same time and it came good. I haven't bothered to go through them one by one to see which fixed the problem but some may apply to you.
The main expenditure was on a 50mm Skywatcher ED guide scope. I had a little 30mm and I had lost confidence in it.

ZWO almost certainly designed the ASIAIR to work with their own gear so I'm pretty certain that the default calibrations for guiding were set because they give optimum performance so put them back to 2000ms.
You say you changed to a 5A power supply. If you purchased the ZWO power supply and have a pier extension the cable is short enough for the weight of the power supply to be hanging off the mount at some point. That could effect guiding.
I have my 10A Li-ion battery on the 5A socket of the mount and run the AIR off the 3A socket on the side of the mount. Since my ASI 294MM is the only other 12V powered device, it is fed from the AIR 12V output.
The EAF runs off one of the AIR USB ports and the filter wheel and guide camera are connected to the USB hub on the camera because when they are pulling 5V power off the USB port the camera isn't.
You should also have a think about getting some better quality cables and make sure your cable management is spot on. You've been playing around with the setup a bit and one of your cables may have developed a fault.
You should also have a look at the USB jacks on the ASIAIR because I've read that there is a fault that develops where the USB jack connects to the AIR.

Kevin_A

AdrianW unfortunately Asiair was designed well before ZWO sold any harmonic mounts of their own. The 2000ms max durations were a standard setting derived from phd2 guiding parameters based off of typical 2s guide exposure lengths for worm driven mounts and not at all for faster harmonic mounts. When a harmonic mount guides with 0.5s to 1s exposures there is no point having a 2000ms max duration and after a dither it can actually result in wild oscillations in certain mounts to which has been documented and discussed. As long as your max durations are equal or a bit less than the guide exposure length then that is the correct range for any mount.

AdrianW

Kevin_A. The point being that when they started selling their own mount they remained the default settings.
ZWO has a good record of making their equipment work well and I don't think they would set default settings that they hadn't determined to be optimal.

Kevin_A

AdrianW unfortunately that does not apply to harmonic mounts. They are fairly new to that product line. The settings are ideal perfect standard settings for worm driven mounts to which was 99% of the market at the time they introduced asiair and still is 90% of mounts used with asiair. They still will use these standard settings as they want to keep it simple. If you know a lot about strain wave gears you would understand why the standard settings they use for durations are not ideal for the AM5. I asked zwo why they do not use seperate data for their mounts and they said they want to keep simple standard settings and have told individual users to reduce max durations down to 1000ms with AM5 mounts in quite a few posts. Cheers!

Kevin_A

AdrianW the main thing to remember about SWG mounts is that non are the same and you cannot use the same settings for all that work great for others so it is up to users to learn about their own mounts and what works best for them. 3 years ago 99% of PHD2 users used 2000/2500/2500 as standard settings with worm gear mounts and they still do so today. The only one that changes is the calibration step size setting ms that is based on guide scope FL and guide camera pixel size. I know a few people that standard settings with the AM5 works fine and many that reduced the numbers dramatically to get much better results.

SFG8UeX8

Problem Solved. I'm embararessed to say it because i have spent litterally 2 weeks trying to figure what the problem was.
The camera rotator( i think thats what its called) was loose. It has one thumb screw that if you loosen it will allow you to rtotaTE

Kevin_A

SFG8UeX8 haha… things like that happen to us all… it’s like imaging for hours with a bahtinov mask still on. Glad it is fixed! Good luck!

ASIMount@ZWO

SFG8UeX8 Happy to know your trouble was gone.

MrAstro

SFG8UeX8 Happy for you,
Last year, As soon as I received the AM5, I checked all visible screws and found 2 were loose, They are on top of the saddle plate as I recalled.
Since then, I rechecked all screws in 6 months routine.
Temperature changes+ transportation.. etc. are likely affect the screws.

SFG8UeX8

Thanks guys for your help!

ASIMount@ZWO

MrAstro Thank you for your feedback. We'll pay attention this potential risk during our manufacture, storage and transportation process. We'll get better with your help and support.