Back to forums

Fixing scattered light issue

Russell Croman Astrophotography StarXTerminator Steffen Hirtle GraXpert Processing Deep Sky Artifacts
9 replies•319 views
What should poor Menart do next?
Multiple choice poll 6 votes
33% (2 votes)
17% (1 vote)
17% (1 vote)
0% (0 votes)
33% (2 votes)
0% (0 votes)
You must be logged in to vote in this poll.
Jure Menart avatar
Jure Menart avatar
Hi all

After few days of Ha & Oiii acquisitions I finally checked my result. And of course as always I found an issue on integrated images I have quite nasty scattered light in right top corner. Of course it's on both images so I don't have good reference to use @Adam Block trick to replace part of the image

I couldn't find the guilty star (I assume it's a star and not reflections from nearby light sources - as my previous project was not far away on the sky and I didn't see this issue at all).

Lucky my acquisition is not done yet (I think I am somewhere in the 50% of acquisition), so I see few options:
  1. At the end simply use CloneStamp and remove it carefully and leave acquisitions as they are now
  2. Rotate camera for 180° - I might have scattered light on both corners but also some good reference to fix it with replacement (it's corner of the image and not the main focus of the image, so I could get away with slightly higher noise I think), bad thing is I double the issue in both corners
  3. Do the right thing and investigate why this reflection and fix it - I will be honest, the nights are so short, I'd like to avoid doing this and just continue with my calibrated setup through this project The lazy way I know
  4. Slightly change position / rotation and try to get rid of scatter light and not loose too much final FOV - problem I see with this is that the scattered light is not visible in single subs, so I am not sure if I wouldn't just make it worse and loose final FOV
  5. Other processing or acquisition ideas?
  6. Throw subs away and get a real hobby


Ha and Oiii integrated images (GraXpert quick background extraction, StarXTerminator & STF applied for easier visibility of the issue):

Helpful Engaging
Oscar avatar
Oscar avatar
that little thing in the corner?

just crop like this when you're done getting all the data:

it'll still look great.
Jure Menart avatar
Jure Menart avatar
Oscar:
that little thing in the corner?

just crop like this when you're done getting all the data:

it'll still look great.

Hi Oscar

Thanks!

I intentionally left out cropping which of course it's valid solution But I agree I might do that at the end, so in this case it's better to just continue with the same acquisitions.

I want to see some ideas of fixing this issues as it's often the problem with our pictures.
andrea tasselli avatar
andrea tasselli avatar
The practical thing to do is to wait for the crossing of the meridian and the thing will likely disappear (crossing fingers here). You would then have a clean (at least locally) image to use to clone-stamp the reflection away.
Helpful
Anne-Maree McComb avatar
Anne-Maree McComb avatar
andrea tasselli:
The practical thing to do is to wait for the crossing of the meridian and the thing will likely disappear (crossing fingers here). You would then have a clean (at least locally) image to use to clone-stamp the reflection away.

I have the same problem with my reflector.  I'm wondering why crossing the meridian would resolve it?  Wouldn't it just appear in the diagonally opposite corner?
Well Written Engaging
Jure Menart avatar
Jure Menart avatar
andrea tasselli:
The practical thing to do is to wait for the crossing of the meridian and the thing will likely disappear (crossing fingers here). You would then have a clean (at least locally) image to use to clone-stamp the reflection away.

Wouldn't that be basically.the same as 180 degree rotation? Unfortunately at this moment meridian flip happens after the astronomical darkness.
I have the same problem with my reflector.  I'm wondering why crossing the meridian would resolve it?  Wouldn't it just appear in the diagonally opposite corner?

Yes it would appear at opposite corner which means real signal would be stronger then scattered light. And even if not one could use only integration without scattered light for each corner.
andrea tasselli avatar
andrea tasselli avatar
Jure Menart:
Wouldn't that be basically.the same as 180 degree rotation? Unfortunately at this moment meridian flip happens after the astronomical darkness.


Then you're all good. Or you meant after the astronomical darkness is over? You still have about an hour of nautical darkness which is fine with NB imagining.
andrea tasselli avatar
andrea tasselli avatar
Anne-Maree McComb:
I have the same problem with my reflector.  I'm wondering why crossing the meridian would resolve it?  Wouldn't it just appear in the diagonally opposite corner?


Yes, that is exactly. You can either average them or, better, clone stamp the affected areas with the image that isn't affected.
Steve avatar
Steve avatar
andrea tasselli:
Jure Menart:
Wouldn't that be basically.the same as 180 degree rotation? Unfortunately at this moment meridian flip happens after the astronomical darkness.


Then you're all good. Or you meant after the astronomical darkness is over? You still have about an hour of nautical darkness which is fine with NB imagining.

Is nautical darkness OK for OIII data?  I’ve always done H-alpha during that period.
andrea tasselli avatar
andrea tasselli avatar
Steve:
Is nautical darkness OK for OIII data?  I’ve always done H-alpha during that period.


*Yes, but not as good as during the astronomical night.