Excellent PA - Very poor images

Using SharpCap's Polar Alignment feature
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martinclayden
Posts: 8
Joined: Thu Jul 09, 2020 9:31 am

Excellent PA - Very poor images

#1

Post by martinclayden »

Hi all,

Using Star Adventurer, stock Canon 77D DSLR, 200m focal length. Bought SharpCap in late October - first clear, moonless, night yesterday!!

At more or less my first attempt using SharpCap for PA I was lucky enough to obtain "Excellent" - a tribute to the ease of use of SharpCap !

Focus and framing went well too.

However, the first captured image was very poor - showing very significant star trails, and looking through the Polarscope of the SA showed that Polaris was significantly far from the "correct" reticle position. I say "correct", because, prior to using SharpCap I have done a visual PA to achieve reasonable results, so I am familiar with where Polaris ought to be.

So, as a new user, I'm struggling to understand what's gone wrong - any help or ideas much appreciated.

Martin
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Re: Excellent PA - Very poor images

#2

Post by admin »

Hi Martin,

the most likely cause is a dragging/pulling cable meaning that the guide scope is shifting slightly as the mount is rotated - this throws the SharpCap alignment calculations off. More on this (and how to tell if it is happening) here : https://www.sharpcap.co.uk/sharpcap/fea ... leshooting

cheers,

Robin
martinclayden
Posts: 8
Joined: Thu Jul 09, 2020 9:31 am

Re: Excellent PA - Very poor images

#3

Post by martinclayden »

Robin,

Thanks for the suggestion, I'll certainly check my cables, the next time its clear perhaps 2021 sometime :(

Martin
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