1600MM odd image effect

ncwolfie

I'm getting some sort of banding or light leak at the top of all my images. Not sure what you would call it. When processing in Pixinsight I thought DBE or ABE would take it out but it does not seem to help much. Below are two images of the same galaxies 1 processed with ABE 1 with DBE, then histogram stretched. Any thoughts on how to remedy this?

I image at unity gain for deep sky with the 1600mm.

Thanks,

Randy

ncwolfie

This is from a stack of 65 images all exposed for 60 seconds each.

No OAG, Orion mini deluxe guide scope with an asi 120mm-s guide camera.

Also using the ZWO electronic filter wheel, but all these images were taken with the Luminance filter only. The moon was below the horizon for these images. I used a master luminance flat made from 25 flats using a light box, exposures had to be very fast at 0.05 second exposures for flats. I could actually use advice on the exposures for flats on this camera although this seemed as good as anything else I tried. One second for liuminance was way over saturated.

I used a master dark made from 25 dark exposures at 60 seconds each.

My bias was a master bias made from 100 bias frames.

The resized master flat is shown below in jpg format.

Thanks,

Randy

Sam@ZWO

can you show the dark file?

ncwolfie

Here is the master dark file. The first image is a stretched version of the dark file for detail. The second image is the actual master dark used. The stretched version looses a little noise when saved as a jpg. The fits file is to large to post though.

Regards,

Randy

Sam@ZWO

you can tell from the dark frame that there is no light leak from your camera

so the banding issue maybe related to light pollution or reflection of moon light

ncwolfie

I will look for stray light tonight, I know it wasn't the moon as it was not out. Maybe a power light indicator is giving a glow somewhere is all I can really think of.

Thanks

Randy

moonprince

I think it looks like some reflection.

elken2004

Hi, I have found if you have a longer USB3 leads, you need to slow the USB rate down, as in sharpcap .

I have found that stops the horz banding. you did not specify what capture package you were using.

I was using a asi1600mc.

thats a lot of data in one xfer between frames, ahh also giving some time between frame grabs helps too