Re: Can't get less than 1" total RMS


Henk Aling
 

On Wed, Jul 21, 2021 at 08:19 PM, Alexander Varakin wrote:
I also have G11 with AT10RC which is about #40 in total.
My RMS is between 0.6" and 1.2", depending on conditions. I am fairly happy with my images.
Here is my astrobin page, showing my images: https://www.astrobin.com/users/avarakin/
Very nice images indeed!  I noticed that your integration times are about 10 to 15 times mine.  And that you use PI, which has star minimization features.  If that explains the difference then I may be doing OK with 1" RMS?

What is the problem with your images exactly - elongated stars?
No the stars are round but larger than I like.  Blurry, not razor sharp.

Are you using OAG? With your FL, I would strongly advise switching to OAG.
Your issues may be caused by flexure in different components between the main camera and the guide camera.
Yes I have a QHY medium size OAG with an ASI120MM mini.

You will have to upgrade your camera to 174 chip in case if you go to OAG: 120 chip is tiny for OAG.
It works for me but just barely, sometimes I have to look for stars.

PHD2 works great with Kstars for me. 
I try guider of Kstars once in a while and still revert back to PHD2: PHD2 is much more robust.
Did you try the multi star guiding?  It works pretty well.  I switched to PHD2 and it gave me larger errors (this was with single star though).

Did you try collecting unguided logs from PHD2 and analyzing them using PHDLogViewer?
Once you do, you will see your periodic error and the components of it. This will help you to troubleshoot the culprits.
Yes I have used the PHD logviewer.  I use Ekos' log, it is an easy to use spreadsheet, you can plot graphs in Excel.
I wrote a Scilab optimization script to find the main frequencies in the time domain.

I doubt you need to increase micro-stepping - 2130 chip has interpolation to 256 micro-steps.
I changed it from 32x to 64x.

Your motor might be the reason for your problems too - it has pretty low torque. 
Look for threads here, there is some very good motor from Oriental motors. It is costly but has much higher torque.
Thanks that's good to know, I was wondering about that.

The trouble about building your own gear is that you can't tell the vendor that their product doesn't work because you are not using it according to spec with the vendor's tools.  I was wondering if the Gemini motors are simply stronger and work better.

Join main@onstep.groups.io to automatically receive all group messages.