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 Post Posted: Fri Nov 10, 2017 7:02 pm 
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Currently I'm dealing with an issue in which my images show wide spikes projecting from bright stars at symetric angles, as illustrated in the attached file. I have a Celestron EdgeHD 8, a Celestron .7 reducer, and a ZWO ASI1600MM. So far, in discussions with other people, and reading threads in CN, I have learned that this results from diffraction and reflections within the ASI1600 because the sensor does not have an A/R coating. I see that other people have this problem, especially with the ASI1600, and it is a known issue. But it seems especially severe in this photo. So, I am looking for ways to deal with the problem. This photo was captured with (20) 30 second exposures via Nebulosity, which I then ran through Deep Sky Stacker, and played with the level and stretching tool only within DSS.


Any suggestions would be appreciated.


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 Post Posted: Sun Nov 12, 2017 5:24 pm 
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I've never seen that on mine. I suspect optics separate from the camera.


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 Post Posted: Wed Nov 15, 2017 12:52 pm 
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maybe from reducer
you can attach the camera only and try again

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 Post Posted: Sat Nov 18, 2017 6:59 pm 
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Thank you for your reply Sam. Removing the .7 reducer from the optical path will be a good experiment. I will perform this experiment. However, I purchased the .7 reducer for an obvious reason. This reason for this purchase persists and I will not consider it an acceptable outcome to not be able to use the .7 reducer.

I also understand that this known issue is not fully under your control, as the Panasonic sensor is manufactured primarily for non-Astrophotography purposes so does not have the anti-reflective coating. Your company does not have the volume of purchases to demand the the sensor manufacturer add such a coating to the sensor. I also understand that other Astronomy camera manufactures have the same issue. I have also heard that whether these reflection problems present themselves is highly dependent upon the exact nature of the optical train. The best we can do is to try to understand this better.

This forum is a good place to exchange this information. I will do some experiments to try to debug my specific setup, and will publish anything I find here. I would appreciate it if your company could look into this problem further, and publish findings, so as to better advise the users on how to deal with the reflections issue.

thanks,

D.T. Gehm


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 Post Posted: Tue Nov 21, 2017 1:57 pm 
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thomehm wrote:
Thank you for your reply Sam. Removing the .7 reducer from the optical path will be a good experiment. I will perform this experiment. However, I purchased the .7 reducer for an obvious reason. This reason for this purchase persists and I will not consider it an acceptable outcome to not be able to use the .7 reducer.

I also understand that this known issue is not fully under your control, as the Panasonic sensor is manufactured primarily for non-Astrophotography purposes so does not have the anti-reflective coating. Your company does not have the volume of purchases to demand the the sensor manufacturer add such a coating to the sensor. I also understand that other Astronomy camera manufactures have the same issue. I have also heard that whether these reflection problems present themselves is highly dependent upon the exact nature of the optical train. The best we can do is to try to understand this better.

This forum is a good place to exchange this information. I will do some experiments to try to debug my specific setup, and will publish anything I find here. I would appreciate it if your company could look into this problem further, and publish findings, so as to better advise the users on how to deal with the reflections issue.

thanks,

D.T. Gehm


thanks for your understanding
you are absolutely right :D

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