Horizon camera artefact

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Jean-Francois
Posts: 361
Joined: Sun Oct 13, 2019 10:52 am
Location: Germany

Horizon camera artefact

#1

Post by Jean-Francois »

Hello,

I do my first try with the Live Stack on the Orion nebula.
Here an image "Save exactly as seen" from the Live Stack menu.
I find something interesting ... I use the "Test Camera 1 (Deep Sky)" for import the image back in SharpCap for the live processing.

Does somebody have similar artefact in horizontal lines on a Atik Horizon-C (first generation) ?
The bright star in the bottom has slightly the same artefact. Is that a simple effect that the nebula center is very bright ?

One additional question ... how to eliminate the very small dots on the image ? I perform dark image capture with the same settings before using it in the Live Stack. But the dots are all the time visible.
Stack_170frames_11s_WithDisplayStretch.jpg
Stack_170frames_11s_WithDisplayStretch.jpg (768.69 KiB) Viewed 1324 times
Equipment: 10" Newton (F4), ASA corrector-reducer to 2.8, Atik Horizon-C camera, EQ8-Rh mount. Note that the Orion nebula was only few degree above buildings. The image is without any other image processing. In the future, I will take a flat before doing the Live Stack ... it will help to reduce the vignetting.

Regards,
Jean-Francois
procyon12
Posts: 253
Joined: Tue Jan 14, 2020 11:32 am

Re: Horizon camera artefact

#2

Post by procyon12 »

Hi Jean-Francois,

Nice shot. I do not know this cam but I think this is banding (for QHY174GPS SC has a very effective banding reduction). See e.g. https://forums.atik-cameras.com/index.php?topic=4364.0

Cheers

Christian
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Re: Horizon camera artefact

#3

Post by admin »

Hi,

do you see the effect if you stretch a single raw frame from the camera?

Robin
Jean-Francois
Posts: 361
Joined: Sun Oct 13, 2019 10:52 am
Location: Germany

Re: Horizon camera artefact

#4

Post by Jean-Francois »

Hello,

I do some images with the Prism software after the Live Stack with SharpCap. Here for comparaison ...
Horizon_image_banding.jpg
Horizon_image_banding.jpg (376.14 KiB) Viewed 1305 times
Upper-left: SharpCap with 60 images 5s = 300s, as seen on the monitor
Upper-right: Prism, one individual image with 5 s
Lower-left: Prism, one individual image 60 s
Lower-right: Prism, average of 21 images with 60 s = 21 minutes.
All images with similar stretch.

Sorry, but I have no individual images from SharpCap Live Stack.

The "banding" is at the same vertical location as the central bright stars.
First, I guess some straylight in the optics that generates this lines, but on the Prism image(s) nothing is visible ... so it is no straylight in the optics.

Christian, thank you for the banding discussion in the Atik-forum.
I guess that the combination of the offset/gain + bright local illumination generates different banding effect.
And I'm sure that the offset/gain settings were different during the Prism session.

SharpCap has a setting for reducing the banding. I use it on the QHY-174-GPS or the QHY-5II camera (sometimes) with success.
But on the M42 images, the effect is not random.

Regards,
Jean-Francois
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