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What might be causing this starburst?

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#1 mjgood

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Posted 18 October 2020 - 11:58 AM

Any thought as to why bright stars have this starburst..

 

It's a very simple imaging train..  William Optics Zenithstar 61 with a flattener, no filters.. the main lens as well at the flattener are spotless, I don't normally use flats as I have a small sensor an no dust specs.

 

I know with my eyeglasses if I clean them without a cleaning solution they will get similar light streaks, is it possible the same is happening with the optics? I normally use air to blow off any dust and I use  specialized microfiber cloth that is for aviation FLIR equipment..

 

 

Thanks in advance...

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#2 sg6

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Posted 18 October 2020 - 12:14 PM

What is the camera?

Many have micro lens or prisms and they can cause the multiple "spikes". So my first thought is the camera itself is the cause.

 

Have seen others ask the same question about the same problem. Shame I cannot recall the final conclusion of any of the posts/questions.



#3 bobzeq25

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Posted 18 October 2020 - 12:14 PM

Nature of the camera.  If you use "too long" subexposures, it gets worse.  Shorter subs (and more of them to maintain the same total imaging time) makes it better.  So does more dynamic range, generally achieved with a specific camera by lower gain.  There are exceptions.

 

Calculating the proper length of subexposures is a different topic.


Edited by bobzeq25, 18 October 2020 - 12:16 PM.


#4 mjgood

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Posted 18 October 2020 - 12:24 PM

The camera is an Altair 183C TEC, the only glass on that is the window over the sensor, I believe it's an IR-UV blocking filter.. the star is in Pleiades, the spikes happen on 120s as well as 240s exposures.. I probably could have gone as low as 30 seconds exposure since it's so bright, I will try lower times...


Edited by mjgood, 18 October 2020 - 12:26 PM.

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#5 TxStars

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Posted 18 October 2020 - 04:28 PM

The best place to start is with shorter exposures.

This will reduce the flare and the slight star trailing.




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