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Newton Rings w/ Barlow

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8 replies to this topic

#1 austin.grant

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Posted 14 June 2019 - 04:37 PM

Greetings all!

 

I got out to do some Ha imaging today with a camera I just acquired, and I'm getting some pretty prominent Newton Rings. The camera is a Skyris 236M, and it's on a double-stacked SM II 60. I don't see any issues at native focal length, but they are very obvious with a barlow. I've got a couple of those cheap Celestron barlow's that come with the Plossl kits. With one barlow, the rings are bad, and with stacked barlows they are twice as bad. They don't align with each other in the stacked barlow state, so I'm hoping that might indicate it's just the barlows causing the issue? I'm attaching a shot with one barlow below.

 

Sun_100621_0118.jpg

 

 

I'm wondering if I should try another barlow first, or try to find a way to tilt the camera and see if it resolves the problem. Thoughts? 



#2 austin.grant

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Posted 14 June 2019 - 04:41 PM

And for fun, here's a 2-panel mosaic full-disk image from this morning. It's been years since I've done any imaging, and I'm very rusty. Didn't process any prom stuff yet. I've got to go and watch some of the excellent tutorials that some of you guys have produced. 

 

Sun_101238_lapl5_ap541-copy.jpg



#3 rigel123

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Posted 14 June 2019 - 08:43 PM

Have you tried flats?  I use the Flat option in Firecapture and it works well with close up shots to negate the rings.


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#4 austin.grant

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Posted 15 June 2019 - 12:50 PM

Cool, thanks for the tip on the Flats!


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#5 marktownley

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Posted 16 June 2019 - 03:26 PM

Just tilt the camera...


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#6 rigel123

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Posted 16 June 2019 - 03:47 PM

Just tilt the camera...

How much?  I have the tilt adapter and can't seem to get rid of those rings.  I wouldn't think you had to tilt it too much.



#7 austin.grant

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Posted 16 June 2019 - 04:24 PM

I shimmed the sensor by several degrees, but there was no change. The flats worked well enough that I probably won’t order the tilt adapter.
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#8 MAURITS

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Posted 17 June 2019 - 09:34 AM

Use flats and a interference eliminator, problem solved.  smile.gif



#9 marktownley

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Posted 17 June 2019 - 04:39 PM

How much?  I have the tilt adapter and can't seem to get rid of those rings.  I wouldn't think you had to tilt it too much.

I've wrote an article on my website about newtons rings that might be useful  https://brierleyhill...tons-rings.html




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