Banding on flats with ZWO6200MM

bodon

Gday all
I recently purchased new filters, FW and 6200mm. I do not have light leaks as I have done many tests. I have used a trace panel , Giotto flat field generator and sky flats and still get banding issues with new filters, new filterwheel and new 6200mm. Used gloves and mask to put together so no 'smudges' of any kind. I have even tried different power banks for power, rotated my flat field generator and rotated my captains wheel on my telescope, but banding in my flats is plain to see. It very apparent in Ha and Sii. Its also visible in the other filters with an STF stretch in pixinsisght. I have sent numerous fits and pictures to the shop where I purchased my gear which they are still looking at to try and find a cause. As the gear (apart from the scope) is brand new and bad weather I have only managed to get seven fit files of the Carina Nebula. I have not been able to stack the lights just to see If it effects the final photo outright.
I can only assume it will corrupt the final photo as It can only be the camera.
I was previously using the 2600mm with no issues.
This camera is very expensive and Im not happy at all.
I started a thread on Astrobin to see if I could also get an explanation. Seems as If some else has the same banding using the same camera? https://www.astrobin.com/forum/post/196372/
This is my banding. Same banding using Gain 0 or 100
![
Im using an Askar FRA500
Antlia Filters
ZWO Filter Wheel
ZWO Camera
Can some guru try and explain what is occurring please. Ta Regards

bodon

Im surprised I have had no response; ZWO tech have put this into the too hard basket? It seems as if ZWO like to sell these expensive cameras but have no time for some feedback? Why bother to have a forum?
If you do have time, maybe you can take a look at my flat fit files to try and determine the cause. These flat fits are taken with a flat field generator and the other flats are sky flats.
https://1drv.ms/f/c/1590e3920719410b/Et4m8wbpQtxHnc7XACQTTPsBgXCve60och6RALIGILcqbw?e=MDbKBT
https://1drv.ms/f/c/1590e3920719410b/Eln30JtecXRLowN-L5PHY8EBeH8zmwujVvljlpauEl9Klw?e=Sx4Ejh
Regards

Tech@ZWO

Sorry for the late reply, and thank you for the detailed info.
Could you please try rotating the filter in its thread and check if the banding pattern changes. You can test it at different angles — for example:

Fully tightened
Loosened and rotated about 90 degrees
Then about 180 degrees
This will help us determine whether the issue is related to filter alignment or internal reflections.
If the banding remains the same, please send the original FITS files showing the issue to our technical support, we’ll analyze them in detail.
https://support.zwoastro.com/

bodon

Hi
Appreciate the response. Ta
I have tried what you suggested but the pattern remains the same. I have turned the camera/optics and yet the pattern remained fixed. The pattern is cyclic/repeating pattern and seen strongly in Red Ha and Sii. Its the red wave lengths. It points to the camera sensor causing interference.
Regards

Tech@ZWO

bodon The fringe patterns you noticed in the image is a well-known and common physical effect in CMOS sensors under certain lighting conditions. This is called "interference fringes" and is more likely to occur in the near-infrared range. When monochromatic light enters the thin silicon layer of the sensor, internal reflections can cause interference patterns to form. This is a general phenomenon that may appear in many CMOS sensors, especially those with back-illuminated or thin-layer structures.