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I agree

PI - Ha regions disappear after SCNR

16 Nov, 2018 10:38

so this is probably me still learning the ropes, but I had the following issue:

I am currently collecting data for M33, first batch  was(1h of L/R/G/B each at F5.5). After combing and photometric color calibration of R/G/B, I see clear hints of the various Ha regions, some very strong, some fainter. The image at this stage has a slight green tint. After stretching etc I would then run SCNR (green) - which unfortunately erases most of the Ha signal (except the very strong region).

Any idea why and whether there is anything I could do to avoid that? Is the overall signal just to weak, or am I actually doing something wrong here?

16 Nov, 2018 12:34
Try SCNR after chrominance noise reduction and/or reduce amount of SCNR.
16 Nov, 2018 17:15
am I actually doing something wrong here?
Are you using SCNR Green at 100% strength? I usually start at 50% and then undo and try a different value if it seems to be destroying signal rather than just noise.  If you still are having trouble you could always apply a stretched, inverted luminance mask first and then use SCNR- it should mostly be working on the sky background anyways.
18 Nov, 2018 16:12
I don't use SCNR if isn't strictly necessary, this eats your data. I prefer neutralize color while be possible.
Edited 18 Nov, 2018 16:13
19 Nov, 2018 06:18
Yes, based on the feedback here, I was able to solve my issue. Ended up using SCNR at 0.7.
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