|
If we are talking Flats then the problem isn't really a problem it may well be a hot spot in the flat or just a dust mote which is causing this to happen.
The one thing which must be taken is darks or bias frames. Without these the flats will be near useless.
If we are talking the light frames after flats have been used to calibrate then I suggest you just continue to combine then straighten out the colours after calibration and combination.
Using RAW CCD images is a little different to using a DSLR which does a lot of processing of each frame before you even see it. Remeber the CCD image is RAW, Very RAW and needs a little more massaging but gives much improved overall results.
Flats can be a bugger to get just right. Keep at it.
|