Focus over Sun disc - Help to solve Newton's Rings

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davidem27
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Focus over Sun disc - Help to solve Newton's Rings

Post by davidem27 »

Hello Ladies and gentlemen,
how do you judge the focus on all over the disc?

https://drive.google.com/file/d/1Sj2_W4 ... sp=sharing

I used the tilter for the first time to avoid Newton's rings and it seems, somewhere on the disc, the focus lacks of precision.

What do you think about?
Last edited by davidem27 on Sat Jul 03, 2021 8:09 am, edited 1 time in total.


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Re: Focus over Sun disc

Post by Montana »

I would have thought that the Sun would have the same focus all over, I've never had a problem with this. However if you are using massive tilt this could be a problem. Certainly the left side looks more out of focus than the right so something is not square :(

A nice disc though :) :hamster:

Alexandra


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Re: Focus over Sun disc

Post by davidem27 »

Thankyou Alexandra for replying.
Your look puts one heavy cent to my doubts.

The entity of the tilting is definitely thick.
tiltingEntity.jpg
tiltingEntity.jpg (147.26 KiB) Viewed 442 times
But this was the first position I figured out that removed Newton's ring.
Maybe I have to try again with another angle.
But, sincerely, I don't think it will work.

Do you have any other tip to remove Newton's rings?


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H-alpha: Lunt LS50T Ha BF600, 120 ED modified by Lunt etalon. Thousand Oaks 0.9 Å Prominance filter
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Re: Focus over Sun disc - Help to solve Newton's Rings

Post by H-Alpha »

Hi Davide!

I was also fighting against the N.R. the previous days, because they appeared with my new Barlow. I thought that because it is a considered quality one would not present N.R.s. I found relatively easy (although tiring...) to remove them with some flats in firecapture, but I never had them in full disks, so there it might be more difficult? Did you try?

Best wishes,
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Re: Focus over Sun disc - Help to solve Newton's Rings

Post by davidem27 »

H-Alpha wrote: Sat Jul 03, 2021 11:15 pm to remove them with some flats in firecapture, but I never had them in full disks, so there it might be more difficult? Did you try?
Hello Alexandros and hello to everyone,
I was away in last weeks so didn't check forums.
I do not know what is the better way to apply flat images to Sun disc images.
I have to find out what are the most common and useful ways.
I saw some youtube videos from a solarchat user but I have to better understand/apply the software process.

How did you tried?

Do anyone else know how to effectively remove Newton's rings from full disk images?

Thanks so much and glad to be here again.


White light: Skywatcher 120 ED and Borg 76 ED with Baader Herschel Wedge and filters
H-alpha: Lunt LS50T Ha BF600, 120 ED modified by Lunt etalon. Thousand Oaks 0.9 Å Prominance filter
Calcium II K: Lunt B1200

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Re: Focus over Sun disc - Help to solve Newton's Rings

Post by Merlin66 »

David,
I had a thread on the subject of full disk flats and NR.

viewtopic.php?f=33&t=31335

FireCapture flats worked well, but for ease of use I’ve gone back to using the T2 tilter at maximum angle.
This is with the TV x2.5 PM and the ASI1600.


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Re: Focus over Sun disc - Help to solve Newton's Rings

Post by MAURITS »

David, I need always a tilter when I do Ha imaging.


Regards,
Maurits

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