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


On Wed, Jul 21, 2021 at 11:35 PM, Alexander Varakin wrote:

Given that the stars are round, I think the mount is not the culprit. 

I hope you realize that you are imaging at 0.56'' per pixel and that is not easy.

Possible culprits most likely are
1. Poor seeing
2. Poor focus. How do you focus ?
3. Poor optics

Yes, I use a lot of sharpening methods in PI - deconvolution and others.

Can you install demo version of PI and do DynamicPSF on your stars and share results?

Then I can compare with my results. 

The seeing may have been poor with the very warm days we had here.  I took an image tonight, about 40x60s subs with recycled biases and flats.  Guiding was ddone mostly with Ekos, several with PHD2, both multi-star.  Ekos seemed to guide better so I went back to that.  I did not counterbalance enough in RA because I wanted to play with loose clutches.  As a result the stars are oblong in RA but not too bad.  The total RMS was pretty bad, 1.5" RMS.  You can tell that the stars are blurry.  Here is a link: | Photo .  This is on another IO board so just in case you can't see it, here it is included (at poor resolution, I don't know how to preserve it).  I will get a PI teaser subscription later but not now because in a week I will go on vacation so I won't get enough time out of it.  I focus with an autofocuser in Ekos, this works quite well.  I collimated the OTA before I started.  The Newt has a Paracorr II CC.  The optics are fine.

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