Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Auto-guiding

  • Please log in to reply
13 replies to this topic

#1 yoyoToTo

yoyoToTo

    Explorer 1

  • -----
  • topic starter
  • Posts: 84
  • Joined: 07 Oct 2022
  • Loc: Earth

Posted 07 December 2022 - 05:09 PM

Are these numbers good? 

 

I finally got my guide scope into focus, and got PHD2 to play nicely. 

 

guide

 



#2 qswat72

qswat72

    Viking 1

  • *****
  • Posts: 577
  • Joined: 02 Sep 2020

Posted 07 December 2022 - 05:18 PM

It depends on your image scale. If you’re still getting sharp stars then those numbers will be fine. That said, usually most people will try to aim for lower numbers around the 1.00” mark.
  • yoyoToTo likes this

#3 acrh2

acrh2

    Surveyor 1

  • *****
  • Posts: 1,741
  • Joined: 16 Mar 2021

Posted 07 December 2022 - 05:20 PM

No, these are awful. In all likelihood, PHD2 miscalculated your guide system pixel scale.

What is your guide scope/camera, and which numbers did you input into PHD2 for focal length/pixel size?


  • Skysmacker, bendgrampie and yoyoToTo like this

#4 pyrasanth

pyrasanth

    Fly Me to the Moon

  • *****
  • Posts: 6,443
  • Joined: 08 Jan 2016

Posted 07 December 2022 - 06:01 PM

No, these are awful. In all likelihood, PHD2 miscalculated your guide system pixel scale.

What is your guide scope/camera, and which numbers did you input into PHD2 for focal length/pixel size?

Remember to be kind- we all have to work out our Gremlins! and the OP is a beginner with a lot of challenges to work around.

 

As noted the first thing to check is that the focal length of your guide camera and the pixel size is correctly recorded in the PHD2 interface settings.

 

Try and get as good a polar alignment as possible. This will help PHD2 to not have to work so hard on the guiding. When you have a calibration for the guiding use the guiding wizard to fine tune the guide settings. I would initially accept the recommendations from the wizard then look to fine tune from there. Don't be tempted to use exposures that are too long. Set a binning level on your guide camera that puts you above 0.5 arc sec as recommended in the wizard setup of PHD2. Big chunky pixels can be useful. On my camera because the pixels are really small on my C14 I can just about scrape 0.5 arc secs per pixel- but ideally I wanted 0.,8 arc secs per pixel.

 

Most mounts, even if not so good quality should put you around 1 arc sec guiding or under. Don't be too discouraged- I understand you are just starting out so enjoy working the problem & gain valuable knowledge as you purge those Gremlins.

 

Good Luck!


  • Jim Waters, willm09, erpagris and 1 other like this

#5 yoyoToTo

yoyoToTo

    Explorer 1

  • -----
  • topic starter
  • Posts: 84
  • Joined: 07 Oct 2022
  • Loc: Earth

Posted 07 December 2022 - 07:06 PM

Ah. I did not set any settings at all. I just calibrated and pushed the button. 

 

It's an Omegon 50mm guide scope and the camera is an Omegon 1200MM. 

 

I had quite a bit of difficulty getting it into focus, and it's probably still not completely in focus. Is that also a problem? 



#6 acrh2

acrh2

    Surveyor 1

  • *****
  • Posts: 1,741
  • Joined: 16 Mar 2021

Posted 07 December 2022 - 07:27 PM

Ah. I did not set any settings at all. I just calibrated and pushed the button. 

 

It's an Omegon 50mm guide scope and the camera is an Omegon 1200MM. 

 

I had quite a bit of difficulty getting it into focus, and it's probably still not completely in focus. Is that also a problem? 

You might wanna check what those values (Pixel Size and Focal Length) came out as in PHD2, under Advanced setup/Camera and Advanced setup/Guiding.

You real pixel size is 3.75 micron and real focal length is 200 mm according to the manufacturer. 

 

Anyway, your pixel scale is 206.3 * 3.75 / 200 = 3.87 arcsec/pixel.

According to the screenshot, your total RMS is 0.33 pixels. Which makes it 0.33 * 3.87 = 1.28".

Which isn't bad but also isn't great. You would probably want to tweak both hardware and software to achieve about half that. Which any modern mount, that isn't overloaded, should be capable of doing.


Edited by acrh2, 07 December 2022 - 07:28 PM.

  • Skysmacker, Spaceman 56 and yoyoToTo like this

#7 yoyoToTo

yoyoToTo

    Explorer 1

  • -----
  • topic starter
  • Posts: 84
  • Joined: 07 Oct 2022
  • Loc: Earth

Posted 07 December 2022 - 07:44 PM

It probably didn't help that by the time I'd managed to get the main camera into focus, it was hanging about 50m out the back of the telescope, and I forgot to rebalance it. Boy, was it back-heavy when I checked it just now! 

 

But in my defence, it was -2*C outside and I couldn't feel my toes. 

 

I've updated PHD2 from 50 to 200mm, and from 0.10 to 3.75 microns. 

 

Thanks! 

 

Should I mess with the binning? 



#8 jpengstrom

jpengstrom

    Apollo

  • *****
  • Posts: 1,325
  • Joined: 08 Feb 2021
  • Loc: North Texas

Posted 07 December 2022 - 07:53 PM

It probably didn't help that by the time I'd managed to get the main camera into focus, it was hanging about 50m out the back of the telescope, and I forgot to rebalance it. Boy, was it back-heavy when I checked it just now! 

 

But in my defence, it was -2*C outside and I couldn't feel my toes. 

 

I've updated PHD2 from 50 to 200mm, and from 0.10 to 3.75 microns. 

 

Thanks! 

 

Should I mess with the binning? 

Don't mess with the binning of the guide camera.  Just balance your scope on the mount in both Declination and Right Ascension and then try your guiding again.


  • yoyoToTo likes this

#9 jpengstrom

jpengstrom

    Apollo

  • *****
  • Posts: 1,325
  • Joined: 08 Feb 2021
  • Loc: North Texas

Posted 07 December 2022 - 07:57 PM

Oh, another question I have, do you have multiple green squares in the PHD2 star viewing window?  If not you can enable multi-star guiding (it should be enabled by default).  Under the Guide menu select Advanced Settings.  Then on the Guiding tab of the window that pops up make sure "Use multiple stars" is checked.


Edited by jpengstrom, 07 December 2022 - 07:57 PM.


#10 acrh2

acrh2

    Surveyor 1

  • *****
  • Posts: 1,741
  • Joined: 16 Mar 2021

Posted 07 December 2022 - 08:03 PM

It probably didn't help that by the time I'd managed to get the main camera into focus, it was hanging about 50m out the back of the telescope, and I forgot to rebalance it. Boy, was it back-heavy when I checked it just now! 

 

But in my defence, it was -2*C outside and I couldn't feel my toes. 

 

I've updated PHD2 from 50 to 200mm, and from 0.10 to 3.75 microns. 

 

Thanks! 

 

Should I mess with the binning? 

I wouldn't mess with the binning. The camera is sensitive enough and the pixel scale is on the higher side already.

I use a gain of 60 and exposure time of 1.5 sec and it seems to work well. I think your gain is the same as ZWO gain, but in case that it isn't, my 60 gain corresponds to a full well of 1 ke.

 

You should have iPolar, so you should be able to achieve an excellent, <0.5 arcmin, polar alignment with ease (and speed.) I have one myself, and I calibrate it every 6 months or so by running the calibration routine 5-6 times, then calculating the averages of the RA axis center coordinates, and then inputting those averages manually in Settings.

 

You should then run the Guiding Assistant for a few minutes and basically let it choose the right settings for you.


  • yoyoToTo likes this

#11 yoyoToTo

yoyoToTo

    Explorer 1

  • -----
  • topic starter
  • Posts: 84
  • Joined: 07 Oct 2022
  • Loc: Earth

Posted 08 December 2022 - 02:10 AM

Oh, another question I have, do you have multiple green squares in the PHD2 star viewing window?  If not you can enable multi-star guiding (it should be enabled by default).  Under the Guide menu select Advanced Settings.  Then on the Guiding tab of the window that pops up make sure "Use multiple stars" is checked.

Yup I have many green squares. 

 

I also have a 99% full moon to deal with, behind the scope, and light pollution. And no filters. 

 

So as usual I'm making it really easy for me to succeed. 


  • jpengstrom likes this

#12 jpengstrom

jpengstrom

    Apollo

  • *****
  • Posts: 1,325
  • Joined: 08 Feb 2021
  • Loc: North Texas

Posted 08 December 2022 - 10:13 AM

So as usual I'm making it really easy for me to succeed. 

lol.gif


  • yoyoToTo likes this

#13 matt_astro_tx

matt_astro_tx

    Fly Me to the Moon

  • -----
  • Posts: 5,352
  • Joined: 19 Jan 2021
  • Loc: Dallas, Texas

Posted 08 December 2022 - 12:56 PM

I had quite a bit of difficulty getting it into focus, and it's probably still not completely in focus. Is that also a problem? 

Guidescopes don't have to have pinpoint focus.  It's ok if it's a little soft.  Honestly I haven't refocused my guidescope in months.


  • yoyoToTo likes this

#14 yoyoToTo

yoyoToTo

    Explorer 1

  • -----
  • topic starter
  • Posts: 84
  • Joined: 07 Oct 2022
  • Loc: Earth

Posted 08 December 2022 - 05:09 PM

This was the result by the way:

 

ELEPHANT, 2022 12 07, 103x30L, iOptron CEM1207040, ATR3CMOS26000KPA average stacked

 

The stars toward the middle don't look too bad, do they? All things considered. 

 

I picked on this target because it was in the opposite direction to the moon.

 

Can anyone explain the weird repeated marks in the image? At first I figured it was just dust but it's the same thing in several places. What would cause that? 

 

Also I have a mysterious red line. I presume aliens. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics