Newton rings there or not depending on the camera used

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daniele_bonfiglio
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Newton rings there or not depending on the camera used

Post by daniele_bonfiglio »

Hi, my name is Daniele Bonfiglio, I live in Italy and this summer I purchased a Daystar Solar Scout DS with which I am having a lot of fun!
For imaging, I have always used a mirrorless camera (a Fujifilm X-T30) without any Newton rings issue. Recently a friend of mine has lent to me a ZWO ASI178MM camera, and with this and the same scope I get Newton rings. See the two pictures below taken on the same day (December 22 2021).
Do you know why Newton rings should appear with a camera and not with the other? (I have made a simple test and see that with the ASI Newton rings go away by tilting a bit the camera while holding it in the hand attached to the scope)
Best, Daniele

Using the Fujifilm X-T30 mirrorless camera (stack of 400 best frames)
Using the Fujifilm X-T30 mirrorless camera
Using the Fujifilm X-T30 mirrorless camera
sun_20211222_tris.jpg (5.96 MiB) Viewed 2294 times
Using the ZWO ASI178MM camera (just a single frame)
Using the ZWO ASI178MM camera
Using the ZWO ASI178MM camera
Capture_00003.png (3.29 MiB) Viewed 2294 times


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Re: Newton rings there or not depending on the camera used

Post by Montana »

A very warm and sunny welcome Daniele :hamster: the first image is a beauty!!

Unfortunately yes, some cameras chips are bad for Newton's Rings. I have several cameras and some are way worse than others, even on the same equipment. It is not necessarily the chip either, but sometime the coating the chip have on them. So it can vary between camera chip, or same chip and different camera manufacturer. You will have to use a tilt adapter with this camera I think viewtopic.php?f=7&t=21501

Alexandra


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Re: Newton rings there or not depending on the camera used

Post by daniele_bonfiglio »

Dear Alexandra, thank you very much for the warm welcome!
Indeed, I have just found this by Googling on internet: "The basic cause is the design of the camera being use. The interference between the built-in cover plate and the underlying silicon based chip."
Many thanks for the link, with the very useful review about Newton rings and the tilt adapters!
Best, Daniele


Solar scopes: Daystar Solar Scout DS 60/930
80mm f6 achromatic refractor with Daystar Quark from the Solar Scout
Scope: Skywatcher Maksutov-Cassegrain 127/1500
Mount: Skywatcher AZ-GTi
Camera: Fujifilm X-T30
Instagram: @daniele.bonfiglio.astropics
Location: Montagnana, Padova, Italy
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Re: Newton rings there or not depending on the camera used

Post by marktownley »

Welcome to the forum! Yes, you need to tilt the camera to get rid of Newtons rings.


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Re: Newton rings there or not depending on the camera used

Post by daniele_bonfiglio »

Thank you Mark, yes, I will see if I can get a tilt adapter. Best, Daniele


Solar scopes: Daystar Solar Scout DS 60/930
80mm f6 achromatic refractor with Daystar Quark from the Solar Scout
Scope: Skywatcher Maksutov-Cassegrain 127/1500
Mount: Skywatcher AZ-GTi
Camera: Fujifilm X-T30
Instagram: @daniele.bonfiglio.astropics
Location: Montagnana, Padova, Italy
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Re: Newton rings there or not depending on the camera used

Post by OregonAstronomer »

Your image with the X-T30 is absolutely gorgeous!

In addition to the tilter, there are a couple of other things you can try. Some capture programs (SharpCap is the one I use) allow you to take a flat-field image (which includes the Newton's rings) and subtract it from each video frame coming in from the ZWO video camera. Other programs, AutoStakkert in particular, will subtract a flat-frame during stacking. Either way, the fixed ring pattern is removed. It works better for images where the entire field is filled with sun. For whole disk images that include dark sky background there is another approach. It involves using the hand control of the mount to move the scope by random small amounts during the exposure. Since the Newton's rings are fixed, when the stacking software aligns the frames with the sun at a fixed point, the rings end up in different places and are averaged out in the final stack. I've completely eliminated rings in this fashion. Granted it's a bit more work, but it's also nice sitting outside enjoying the sunshine while I manually dither the mount.

Arnie


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Re: Newton rings there or not depending on the camera used

Post by BGazing »

Hm, I have a question.
I have not noticed NRs until now with ASI 1600, with 120 they were very visible in the image. On the other hand, when defocusing with a 2x barlow and with the image completely out of focus I can see a couple of very thick band. They do not move when I rotate the camera. Are they NRs or basically my sweet spot being out of center, or some doublestack reflection? On captured images the outer rim of the bands correspond to the part where the image is slighly off-band.


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Re: Newton rings there or not depending on the camera used

Post by christian viladrich »

daniele_bonfiglio wrote: Tue Jan 11, 2022 1:24 pm
Indeed, I have just found this by Googling on internet: "The basic cause is the design of the camera being use. The interference between the built-in cover plate and the underlying silicon based chip."
This is probably not the correct explanation.

The most probable one is interference fringes building between the two faces of the cover plate of the sensor. More precisally, it seems to be the result of the poor (or missing) anti-reflection coating on the two faces of this cover plate.

It is not possible to have interferences between this plate and the sensor since the sensor is not flat, but covered by an array of micro-lenses (and other stuff).


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Re: Newton rings there or not depending on the camera used

Post by daniele_bonfiglio »

christian viladrich wrote: Tue Jun 20, 2023 7:26 pm
daniele_bonfiglio wrote: Tue Jan 11, 2022 1:24 pm
Indeed, I have just found this by Googling on internet: "The basic cause is the design of the camera being use. The interference between the built-in cover plate and the underlying silicon based chip."
This is probably not the correct explanation.

The most probable one is interference fringes building between the two faces of the cover plate of the sensor. More precisally, it seems to be the result of the poor (or missing) anti-reflection coating on the two faces of this cover plate.

It is not possible to have interferences between this plate and the sensor since the sensor is not flat, but covered by an array of micro-lenses (and other stuff).
Dear Christian,
thank you very much for your comment. It is very good to know the most probable explanation for the origin of Newton rings.
Best,
Daniele


Solar scopes: Daystar Solar Scout DS 60/930
80mm f6 achromatic refractor with Daystar Quark from the Solar Scout
Scope: Skywatcher Maksutov-Cassegrain 127/1500
Mount: Skywatcher AZ-GTi
Camera: Fujifilm X-T30
Instagram: @daniele.bonfiglio.astropics
Location: Montagnana, Padova, Italy
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