Continus problem with polar aling

Using SharpCap's Polar Alignment feature
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forna91
Posts: 6
Joined: Sun Sep 01, 2019 12:54 am

Continus problem with polar aling

Post by forna91 » Sun Feb 16, 2020 11:57 pm

Hello everyone,

I was a little bit skeptical if renew pro license or not, but I did it :evil: .

I have continus problem with polar alignament, and now I made the best test for understand the problem.

My setup:
EQ5 with onstep board
newton 750/150 or ts 65/420 (I use camera scope for p.a.)
Camera asi294mcpro
Guide scope 500/80 with asi 120mc
Polar alignament perfect zone

Too many times I had a bad polar alignamet, olso with refraction active.
Today I made this test:

Using the X reticule I have centered a star, I rotate the camere for have in one direction AR and in the other DEC
Since I use onstep, my mount have a very very accurate traking in fact:

After 30min the object was moved only in Declinatio this mean a bad polar alignament
If tracking was wrong I should see the star moving in the AR ax but, the star stay in perfect position, in fact if I move the mount for recenter the star in the reticle I have no error in AR

As you can see the attachment

Why this??

Other question: My mount have refraction correction for tracking speed, what I have to do? I have to disable the sharpcap ref, correction or my trackion correction or I can enable each two?
Attachments
polar.png
polar.png (8.86 KiB) Viewed 256 times

forna91
Posts: 6
Joined: Sun Sep 01, 2019 12:54 am

Re: Continus problem with polar aling

Post by forna91 » Mon Feb 17, 2020 12:13 am

I have set my coordinate in setting

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admin
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Re: Continus problem with polar aling

Post by admin » Mon Feb 17, 2020 9:03 pm

Hi,

Have you looked at the suggestions on this page for ways to troubleshoot problems with polar alignment?

https://www.sharpcap.co.uk/sharpcap/fea ... leshooting

From your description it sounds most likely that you could be suffering from a problem caused by the guide camera flexing as the mount is rotated around the RA axis. This is most often caused by dangling cables, but can come from other sources. We even had one case where somebody discovered that they had a mechanical flaw with their mount – as they rotated it about the RA axis the stars all moved in a circle around one point and then suddenly they all jumped at a particular position and continued moving in a different circle after that.

Hope this helps, Robin

forna91
Posts: 6
Joined: Sun Sep 01, 2019 12:54 am

Re: Continus problem with polar aling

Post by forna91 » Tue Feb 18, 2020 9:43 am

Tomorrow night I hope I can made some test, is right to do a polare alignament winth long focal (420mm or 750mm in my case)?

The strange thing is that I have the same polare alignament error problem in est or ovest, camera and guide scoper are point to the same object, the cable in teory are not a problem, are banded on the scopes but never say never

In the past I tried to make some star trail, moving the AR by hand, "analysed" with autocad the circle was perfect but neve say never

Keep in touch!

forna91
Posts: 6
Joined: Sun Sep 01, 2019 12:54 am

Re: Continus problem with polar aling

Post by forna91 » Tue Feb 18, 2020 10:56 am

Other problem, I was testing olso in the heart nebula, next to the polaris...
When I can, I will try to see the difference from the polar error from the guide and camera scope

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Re: Continus problem with polar aling

Post by admin » Tue Feb 18, 2020 8:30 pm

Hi,

It's not so much the focal length of the telescope as the field of view that you get with your camera and telescope combination that matters. Ideally the field of view should be at least one degree in each direction, but you can usually get good results down to half a degree in each direction (although it may require longer exposures to get enough stars visible).

Do test out the suggestion on the troubleshooting page about rotating slowly in steps to see if the centre of rotation moves – if that moves during rotation it's a sure sign of some sort of mechanical movement or Flex.

Cheers, Robin

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