Pixinsight "Square Stars"

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Juno16 United States of America
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Pixinsight "Square Stars"

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Post by Juno16 »


I want to share a recent enlightening with any Pixinsight users that might have noticed a similar issue as I was having.

When I first started using PI about 9 months ago, after running the WBPP script to pre-process my data, the brighter stars were "square" or "pointed" looking.

It definitely looked like an anomaly to me. Possibly something wrong in my optical train. I was hesitant to post to the PI forum because of my "newness", so I used DSS to stack. In the DSS stacks, the same "square" stars produced by PI were nice and round. I did some researching and ended up changing some settings in PI for preprocessing or just used DSS for pre-processing.

Just recently, I started using a new scope (Sharpstar 61 EDPHII) with the same camera (ASI 533 MC-P) and reset the PI WBPP script settings back to default. When I generated the first masterlight, I zoomed in and saw the same "square" stars again!

I prepared a masterlight with the WBPP defaults (with "square" stars), another masterlight with the modified settings that I had been using (only slightly "square" stars) and an Autosave.fit with DSS to compare the three.

The WBPP masterlight with default settings had the "square" stars, but had obviously better quality (resolution) than the WBPP settings that had been using trying to minimize the "square" star effect. The DSS autosave.fit had the nice round stars, but the resolution was the lowest of the three in the test.

I posted to the PI forum and here is the link in case you are interested. https://pixinsight.com/forum/index.php? ... ars.17172/

Here is the comparison image that I submitted to the PI forum (I don't think that it can be viewed unless you are logged into the forum). This is a 2x zoom in on a part of the M31 dust lanes with only a screen stretch with no processing.

The PI WBPP with defaults is the image on the left (Square stars). The PI WBPP with the settings that I have been using to get "rounder" stars is in the middle. The DSS stack is on the right.
PI Image Registration1.JPG
I might be the only person that has had/noticed this issue. But just in case you might have noticed a similar issue and were not sure why, here you go.

You might be thinking "Man, what a bonehead", but live and learn!
Jim

Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, Orion SSAG, IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut, N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin: https://www.astrobin.com/users/Juno16/
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