Weird bands with LS80Tha/DSII

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mstriebeck
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Weird bands with LS80Tha/DSII

Post by mstriebeck »

Hi,

I bought the LS80THa/DSII https://luntsolarsystems.com/product/ls80haptdsii/module from Lunt in the hopes of increasing contrast in my solar images. Installation was fairly straight forward. But when I took my first images I noticed some strange bands:

Image

I tried to refocus. Started to pressure tune both etalons from scratch but I always got these bands. Took MANY images in the hopes that it's maybe only temporary. Took images in the afternoon again. But always with the same result. Does anybody know what's going on and how to fix this?

Thanks
Mark


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Re: Weird bands with LS80Tha/DSII

Post by gabrieli »

Hi, Mark

These bands are called Newton's rings and are common with some cameras. The solution is usually to tilt the camera slightly. Some people use a tilter specifically made for this purpose. One of the more economical ones is by ZWO shown at

https://astronomy-imaging-camera.com/pr ... t2-tilter/

Note that you also have to buy a snout to fit into the telescope tube. If you have a ZWO camera, the camera will mount directly onto the device. If not, you have to buy a T2/1.25" holder for it

Lou


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Re: Weird bands with LS80Tha/DSII

Post by Carbon60 »

As Lou says, tilting the camera will usually solve the problem. This is common and nothing to be concerned about.... an easy fix.

Stu.


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Re: Weird bands with LS80Tha/DSII

Post by Merlin66 »

As others have already said, the solution is to use a tilter in the optical train.
I assume you are using an ASI camera?


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mstriebeck
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Re: Weird bands with LS80Tha/DSII

Post by mstriebeck »

Thanks everybody.

It's just weird that I didn't see these before (single stacked). Could it be that the additional contrast that I get with the second etalon makes this more visible? Or did the addition of the DSII create this effect?

Ordered the little tilter. I am using a T2/1.25" adapter for my Point Grey camera and can probably put the tilter between that and the diagonal.


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Re: Weird bands with LS80Tha/DSII

Post by Dave S »

Narrower bandwidth and higher focal ratios will generally exacerbate the problem. And it will be different for different cameras. So putting on the DSii will usually make it worse, and putting on a barlow will make it worse.


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