Help needed with flats
G'day,
I often get this problem with images using flats flats - uneven circles etc.
Imaging scope: sct 9.25" @ f 6.3.
Camera CDS 60s cooled. (ISO 800, -14c).
The flats are taken with a good quality light box at the same configuration and time as the lights. Same camera position etc. I used the same ISO and reduced the exposure so the histogram of the flats matches the lights. I used 20 flats. The image was stacked in DSS. I seem to get this problem mostly when I use the reducer. The reducer was used for the lights and the flats.
Does anyone have any ideas what is happening - thanks for any advice.
Regards,
Tony.
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