PA not plate solving - first step

Using SharpCap's Polar Alignment feature
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charliet
Posts: 1
Joined: Wed Nov 25, 2020 3:29 am

PA not plate solving - first step

#1

Post by charliet »

I have a C8 and an ASI 290 camera, trying to PA.

Process: I PA the scope using the azimuth and latitude knobs to put Polaris centered in the eyepiece. I remove the eyepiece and install the 290 camera. On the PC with Sharpcap, I focus Polaris and move the star into the FOV.
I click on the PA routine, set the exposure to 2 seconds and the minimum star pixel to 4. (See attached image). Sharpcap can’t plate solve.
Are there other adjustments I should make?
Thanks for your help.
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admin
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Re: PA not plate solving - first step

#2

Post by admin »

Hi,

if you are using the 290 camera in your C8 telescope then will not get the polar alignment to work because the field of view is far too small. The typical focal length telescope that you need to work the polar alignment with that camera would be 100mm to 300mm, not the 2000mm of your C8.

Most people use that sort of camera with a 200mm f/4 guide scope, which works nicely.

Hope this helps, Robin
Lobo
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Re: PA not plate solving - first step

#3

Post by Lobo »

Interesting, looking at the image postage. I don’t see the green, concentric circles. I tried polar alignment using an APM guidescope (240 mm FL) and I don’t see them on my screen ether. What not?
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Re: PA not plate solving - first step

#4

Post by admin »

Hi,

the circles appear once SharpCap has been able to recognise the pattern of stars that the cameras picking up against its database of stars around the celestial pole. A number of things can stop this from happening – not enough stars being detected, the field-of-view being either too large or too small, or the telescope pointing too far away from the pole so that the stars in view are outside area covered by SharpCap star database.

Further explanation can be found here: https://www.sharpcap.co.uk/sharpcap/fea ... leshooting

Cheers, Robin
Lobo
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Location: Langley

Re: PA not plate solving - first step

#5

Post by Lobo »

Thank you, Robin. Clearly I need to practice more - if I can ever get a clear enough sky! 👍😊
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SonnyE
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Joined: Sat Apr 18, 2020 5:37 am

Re: PA not plate solving - first step

#6

Post by SonnyE »

When I've had slow solves, or no solves, it's usually (well always) been fixed by checking/adjusting my focusing.
I'm using a ZWO ASI290 MM Mini in my 50 mm guide scope for Sharpcap.
It's very rare I have any troubles with Sharpcap, and it always comes back to my human error. :roll:
So I suggest making sure the focus is good.
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