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What a star

astrophotography
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#1 Jaspalchadha

Jaspalchadha

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Posted 12 February 2020 - 03:25 AM

Hi all

I am wondering if someone can shed some light or similar experience

I am currently using a 14 inch gso RC along with Atik 16200 ccd ( ewf3 FW) standard gso focuser

I have noticed that my stars are not fully round but appear to be slightly chopped off. I’ve Checked for obvious obstructions or tilt... my initial thoughts were the focuser sagging as I have at least 50mm extension tubes to bring the equipment into focus ( camera to Focuser)

If you have a look at the top off the dubhe image around 12 o’clock there is a black mark which looks similar to the star shape.

I’ve collimated various time’s and shape appears to be be the same off the star.

I wonder if my secondary is a little out

Thanks

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Edited by gustavo_sanchez, 12 February 2020 - 07:39 AM.


#2 Eddgie

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Posted 12 February 2020 - 07:38 AM

Take an image with the scope out of focus so that about 5-10 rings are showing. The amount is not critical, you just have to have enough to get a pattern that can be easily seen.

 

Seeing what is causing the problem using in focus stars is very difficult.

Seeing what is causing the problem using an out of focus star is essentially performing a star test, and any aberration in the system will be presented to you.  If there is collimation or centering or cutoff, you should be able to see it.  

 

I often to not re-visit threads like this, so if you post it and no one else can tell you what you are seeing, just PM me with the link or PM me the image and I will take a look at it.


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