Quote:
Originally Posted by gregbradley
I have seen similar with a Baader 7nm Ha filter. In that case I believe it ended up being poor coatings on my particular Baader Ha which generally have a good reputation. Some said it was likely a mismatch of darks and lights but even reshooting darks made no difference.
So its either:
1. defective coatings with holes in them
2. mismatched darks and lights. Can you post your dark?
Also if you use median combine you are less likely to see these sorts of artifacts that thrive if you use sum combine where all defects get added together with no outliers being removed.
Greg.
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Hi Greg
Thanks for your reply. I have the benefit of having the LRGB frames in front of me to compare and it looks as if the holes are in the same place on each frame, so I think what is causing the holes is probably on the sensor rather than the filters?
The CFW10 belongs to Gerald and his LRGB filters are 1 ¼ inch Astronomik and they all appear to be parfocal too!
Here’s the dark frame (5x5 mins).
Cheers
Dennis