[SeeMeade (Colin Meade)]

Help! Heavy color pattern coming through in individual flats with 294MC Pro camera and Optolong L-Extreme filter. I can see a lot chatter online about issues with patterns like this with this combo of the 294MC Pro camera and Optolong light pollution filters but none of the suggested solutions I can find are working for me. I have tried:

- Different flat capture software: SharpCap Pro, NINA, ASI
- Sky flats vs LED Panel
- Different diffuser membranes: t-shirt, paper, bedsheets
- Different exposures from 250ms-25s
- Different gain from 120 to 300+
- Cooling to -20C, 15C or no cooling
- Ticking the box for monochrome flat or not

Replacing the filter with an empty filter drawer solves the issue, but then it's not a "proper" flat and needs different exposure & focus settings?

Any suggestions? I bought the camera second hand on here, and don't have warranty...