Horizontal banding in image

[Moonstruck]

Hello,
Last night I tried imaging the helix nebula with a C11 edge telescope, 0.7 reducer and ZWO asi 294MC color camera, with unusual (and very poor) results. I had two separate (and possibly un-related) issues, as follows:

Issue#1:
I tried livestacking some 2- sec frames to make sure I was on target, and the image had bright horizontal bands going across it. I included a link to one of the frames below. It was originally a FITS file but I saved it as a jpg to ensure you could open it. I also stretched it so you could see the horizontal banding clearly. I included the camera settings for this frame as an attachment. Any idea what the banding is from?

https://drive.google.com/file/d/1Quynnb ... sp=sharing

Issue#2:
Then I exited livestacking and switched to capture mode, and captured 41 20-sec frames. When I went to stack them in deep sky stacker I got a message saying the following:
"Only one frame (of the 41) will be stacked. You should change the star detection threshold to detect more stars and help deep sky stacker find a transformation between the reference frame and the others."

If you have any idea what is causing either of the above problems can you please let me know? It was one of the clearest nights I have ever seen for imaging, so I am sure it wasn't caused from poor seeing or any other atmospheric conditions. Thanks in advance.

[admin]

Hi,

the banding in the short exposure frame reminds me of the sort of effects you get with digital cameras under artificial light sometimes, which in turn makes me think it may be worth checking that the 12V power supply to the camera for cooling is behaving itself? If that power supply is misbehaving and is noisy rather than a steady ~12V, it could feed through into banding in the image. You could try viewing dark images with no 12V power connected, 12V power and cooler off and 12V power, cooler on to see if there is any difference.

There's nothing obvious in the camera settings for your later 30s captures that stands out as wrong, but the display stretch recorded in the capture settings file is quite strong, so it's likely that the actual images being saved would have been very dark compared to what you saw on screen. That could tie in with DSS complaining about finding stars. Do you have similar 30s exposures from previous sessions that you could compare with? (both the settings files to see if something has changed and the images to see if the recent ones really are much darker than usual)

cheer,

Robin

[Moonstruck]

Thanks. For item#1, if I get the banding again I'll try what you have described with the power supply.

For item #2 (deep sky stacker question), I am sure you are correct about the display stretch causing the problem. I need to remember that it does not reflect what is being recorded, and to turn it off before imaging. What you said makes perfect sense... I am sure I imaged with it on and as a result got much dimmer subs that were being recorded. That would also explain the bright pink background I saw while imaging. I took several sets of subs and ruined all of them... operator error!!

Thanks again.