Asiair guide settings, AM5, ASI120mm 120mm/30mm

killernils

Hi! Im having trouble to reach below 1.5”RMS using:
Am5
Guide, ASI120mm with a 30mm/120mm guide scope.
Asiair
WO zenithstar 73, 430mm

I guess this is a quite common setup with AM5 and the guide scope choice?
Any suggestions on Guide settings, exposure settings etc to improve guiding?

I tried to follow this guide, and use 8000 as calibration step.
https://eastwindastro.blogspot.com/2021/02/how-to-adjust-asiair-guide-aggression.html?m=1

Br,
Henrik

Jhaunton

That guide is not specific to the AM5. You should follow the guidance in this forum - basically shortish guide exposures (0.5-1s typically), use multi-star guiding, and turn the RA aggression down to 40% for starters. Your must do a good PA before you calibrate and do your calibration well away from the pole. 8000ms sounds excessive for cal step. PHD will give you a recommended setting if you enter the fl of your guidescope and pixel size of you guide camera. In my case it is 1600ms (400 mm fl and lodestar), I think 2500ms or so should work ok for you. If calibration is taking to long you can reduce the limit from 25" to a smaller threshold.

killernils

Jhaunton
Thanks!
When you say ”PHD will give you a recommended setting…”, do you refer to the one in ASIAIr or the standalone PC version?
And when you say “calibrate” you refer to the guide-calibration i guess? When it does all the “x weast, x east” etc?
Can I do that well away from pole and then slew to my actual target and start tracking there?
Because normally I slew to my target, then start guiding and it automatically calibrates and starts guding. Is there a better setup on how to do this?
I.e calibrate on one part of the sky and guide on another?

I’ll give the forum another search for guidence then, without AM5 as search criteria 🙂
If you have a specific post in mind, please feel free to share!
Thanks for your input!

Jhaunton

killernils
Sorry was slow responding:, see:

https://astronomy-imaging-camera.com/news/systematically-improving-guiding-quality-and-zwo-am5-mount-review.html

BTW I now use PPEC for RA and with 1sec exposures, 40% reactive and 50% predictive found it improved my guiding over hysteresis by about 0.2". My RMS error is now consistently < 0.5" total which is better than I need at my imaging scale.

KC_Astro_Mutt

[unknown] Hi, I have a similar setup to yours, but my guide scope/camera are different. For your setup, a calibration step size of 1800 is suggested by PhD2, assuming you'll calibrate near DEC 0. Leaving the default of 2000 in the ASIAir would likely be fine. For exposure settings, 0.5 seconds is what I keep hearing as the "sweet spot", with aggression settings of 45-50% in RA, and the same for the DEC.

Keep this thread posted, as I'm running thru my own issues in figuring this mount out.

Clear Skies!
Jeff

killernils

KC_Astro_Mutt thanks!
How do I ensure that I calibrate close to DEC0?
Calibrate away from the pole, as Jhaunton suggest?

xxao

Hi, I just received a brand new AM5 and for a second night I am trying to reach any reasonable guiding. I have very similar system except the WO ZS61. No matter what I do, I cannot get under 1.5 for more than a few seconds. I still hope it is my mistake, but very sad evenings so far...

mBuxx

I have the exact setup but a GT81 in place of the scope. I am a noob, but I will share my guide settings in the ASIAIR with you tomorrow if you like.

I routinely achieve sub 1 arc second. Total error is typically between .5-.7. On clear nights It will run at .3-.5.

killernils

mBuxx please do! I appreciate it!
Im still waiting for clear skies…

killernils

mBuxx
Im posting screenshots of my settings, not sure if slew rate(mine’s at Max) during preview is relevant though?!

KC_Astro_Mutt

killernils Yes. Imagine your scope in the "HOME" position, then you would rotate the scope in RA and DEC 90 degrees from that position. You are now at DEC 0. Best calibration is made near the celestial equator.

Kevin_A

8000ms is just soooooo long and not right! 8 seconds per calibration pulse is just way too long. Phd2 calculates it at 1800ms. Zwo default is 2000ms(2s). I use 1800ms with the exact same setup… and with my 240mm guide scope using a smaller pixel 290mm mini cam Phd2 calculates that setup at 700ms due to the higher magnification of the scope fl.
Phd2 tries to do calibration by moving the mount to cover 25 pixels and is accurate when pulsing it 10-14 pulses to cover that distance…. Hence 25/2s equals 12 pulses average which is the recommendation from Phd2.

killernils

KC_Astro_Mutt
Alright, thanks for the explaination. And then I reframe to my target and start the guiding from there, without redoing the calibration?

Clouds everywhere today… I just have to wait..

KC_Astro_Mutt

killernils You got it.

killernils

KC_Astro_Mutt

mBuxx No worries, Im happy to follow, always learns something! I have clouds and fog all day long anyhow! 🙂
I really appreciate that you shared your settings.

And thanks to all you other guys sharing you knowledge! I will use it as soon as I get a clear sky!

mBuxx

Sorry for the late response, it’s been a long day.

First three pictures you posted, my settings are exactly the same. I will post pics of where things differentiate.

I am not sure if a dither setting of 10 px is necessary or not, but it has worked out very well for me in my opinion.

Also, I am not sure how to read this LOL, I just downloaded it for this post. Not sure if its good or not but hopefully someone else will chime in. Also, on this specific night I had a loose tripod leg, doh.

KC_Astro_Mutt

mBuxx The screenshot you posted is only for a single run of a little over a minute. I see that there was a run that lasted 1hr 44min 54s. If you would highlight that and post a screenshot, that will give a better overall idea of long term performance of your settings.

As far as dithering 10px, yeah, it's overkill, but as long as your guiding is recovering quickly, it certainly won't hurt anything.

mBuxx

KC_Astro_Mutt ok thank you, sorry like I said I have no clue how to read this haha.

Here is a longer session I found from a previous day. Keep in mind I believe my tripod leg was still loose. I remember hearing it wobble carrying it out, but when checking everything, everything seemed tight. Although I did not think to check the leg, just the mount.

KC_Astro_Mutt

mBuxx Very nice! I'd be quite happy with either of those runs!

mBuxx

KC_Astro_Mutt ok great! Do you suggest the dither of 10 pixels is okay then? Sorry OP for hijacking your thread, lol.

KC_Astro_Mutt

mBuxx Doesn't hurt. You can try a few runs set at 5, guiding shouldn't be affected, but you should recover from the dither quicker, which will get you more subs.

Kevin_A

mBuxx 2-5 pixels is more than enough for dithering and every 5 images. No need to dither every shot.

mBuxx

KC_Astro_Mutt maybe I will try that. Between the autofocus sessions and the dithering, I was beginning to wonder how much time is lost.