Hello, my name is James and I am experiencing significant halo art of some sort when imaging bright stars (see attachment). The camera is the ZWO ASI1600MM Pro using a ZWO filter wheel with ZWO filters (31mm). The scope is an ES 127mm FCD100. I think this is an issue that has been discussed in the past but I couldn't find where anyone maybe came up with a solution or workaround. Any help would be appreciated since the money is spent, my rig is set up, and there are plenty of bright stars up there to photograph!!
As others have said this is two things.
1) The microlense diffraction pattern is inherent to the camera (its the smaller spots closer to the star).
2) The large circular halo something else. Assuming the filter wheel is screwed directly to the cameras male connector then its too big to be a filter reflection between the sensor and the filter. That leaves three possibilities you have the older ZWO unmounted filter and its edge is not blackened. Or you have the filter in backwards (as is possible with 31mm). Or the anti-reflection coating on your reducer / flatter is poor and its causing reflections from the sensor to the reducer and its not related to the filter all all.
The cure is to try reversing the filter in the holder to try and fix the large halo. If that does not work try masking off the edge of the filter, if that does not work then try imaging without the flattner / reducer to see of the halo vanishes.
As for the micro lense diffraction effect, the only real way to reduce that is with a more expensive narrower filter such as the 3nm Astrodon that will greatly attenuate the star brightness.