Thick Color Bands in Light frames

QHYCCD QHY168C Equipment CMOS Banding
7 replies•245 views
webcubus avatar
webcubus avatar
I've been running a QHY168C for several years and fairly recently, it seems to have developed mysterious thick bands that appear in some light frames. I've tried a number of power supplies, different outlets in my house, separating the camera power from the rest of the rig (I normally run through DC Hub from DeepSkyDad), and nothing seems to help.

I've got a ticket open with QHY support and all they've offered me so far is to increase the offset. I've been shooting gain 10/offset 50 forever and I confirmed that for bias frames the minimum ADU is 4, so I'm not clipping and this seems like an unlikely fix.

Any other suggestions of things to try/check? The attached light frame is 300s with an IDAS NBZ dual narrowband filter - single sub, no calibration, just an autostretch in PixInsight.
Well Written Engaging
BryanHudson avatar
BryanHudson avatar
I've had that issue sometimes with stacked images from my ASI2600MC pro. Two things have helped mesmileoing more flat frames and/or running debayer on the image before doing dynamicbackground extraction
TiffsAndAstro avatar
TiffsAndAstro avatar
I've been running a QHY168C for several years and fairly recently, it seems to have developed mysterious thick bands that appear in some light frames. I've tried a number of power supplies, different outlets in my house, separating the camera power from the rest of the rig (I normally run through DC Hub from DeepSkyDad), and nothing seems to help.

I've got a ticket open with QHY support and all they've offered me so far is to increase the offset. I've been shooting gain 10/offset 50 forever and I confirmed that for bias frames the minimum ADU is 4, so I'm not clipping and this seems like an unlikely fix.

Any other suggestions of things to try/check? The attached light frame is 300s with an IDAS NBZ dual narrowband filter - single sub, no calibration, just an autostretch in PixInsight.

looks like the result of strong moonlight. when were these taken? was the moon in the sky like a big pizza pie ?
jmdl101 avatar
jmdl101 avatar
This looks like a completely normal uncalibrated light with the NBZ filter. The green to red gradient should be eliminated with proper flat frames and the background extraction.
Well Written Concise
jmdl101 avatar
jmdl101 avatar
Yours looks more like the moon may have caused the gradient looking back at some of my own images. What was the moon phase, was this recent under a bright moon? Here's one of mine from a bright moon night. A single 300s uncalibrated light frame, a heavily stretched master flat, and the final processed image. 
Insightful Respectful Concise Engaging
webcubus avatar
webcubus avatar
Thank you for the responses, but I've shot thousands of subs through the NBZ in various moon phases - this post is not about the gradient or color, which I know are normal. It is about the thick, faint alternating yellow and blue horizontal bands through the image. I've drawn lines to try to highlight them better.
Well Written
jmdl101 avatar
jmdl101 avatar
Thank you for the responses, but I've shot thousands of subs through the NBZ in various moon phases - this post is not about the gradient or color, which I know are normal. It is about the thick, faint alternating yellow and blue horizontal bands through the image. I've drawn lines to try to highlight them better.

I didn't even notice those before, sorry about that. Yeah those definitely look like a camera issue, especially if you've tried new cables and power supplies. Can you adjust the usb speed on your camera to a slower transfer speed? I think the few times I've seen people post with similar issues they ended up needing a new usb interface on the camera.
Helpful Respectful Concise
andrea tasselli avatar
andrea tasselli avatar
What is your bias like, or a dark? If it is the camera amplification/ADC stage you should be able to pick it up with a pretty long dark without cooling. Alternatively shoot with a pinhole camera and no tracking to see what is that like (very low signal, long integration).
Related discussions
Weird noise pattern in several sub frames
I was going through some of my sub frames from the other night and came across several subs that contained weird interference noise of some sort. The camera was capturing all night long. At 2:30AM about half way through the session, there were 7 sub ...
Mysterious bands in frames similar to your symmetrical white dot pattern.
Sep 26, 2023
FLAT with a strange pattern, I can't properly correct the LIGHTS / SkyWatcher APO ESPRIT 120 / x0.77 Reducer SkayWatcher / QHYY 268 mono / Chroma 3nm SII 36mm and OIII
Hello, I have a problem I can't seem to solve. If anyone can shed some light on it, I'd appreciate it. I'm testing a new setup: SkyWatcher APO ESPRIT 120 / x0.77 Reducer SkyWatcher / QHY 268 mono / Chroma Ha 5nm 36mm / Chroma SII 3nm 36mm / Chroma OI...
Camera artifact troubleshooting with flat frames and light frame issues.
19 days ago
Dark vertical streaks in stacked image
I've been struggling with trying to understand the source of these streaks I see in some recent stacked images. I'm hoping someone here can offer an idea as to what the source is. I'm hoping it's not the camera itself. My set up is a ...
Similar vertical streaking artifacts in stacked images from camera problems.
Aug 21, 2025
Info Cmos QHY 174M cooled
Good morning everyone. Sorry for my strange English but I use an automatic translator (I'm Italian). I haven't had the camera in question for a long time and I was looking for someone who has or had it to ask for some info on the gain and off...
QHY camera user experiencing technical issues; gain/offset settings relevant.
Sep 17, 2023
What’s Wrong With My Luminance?
I really didn’t want to post another knucklehead question, but I am not sure how to proceed. The title says it all. I am a new mono shooter (Minicam8) and this is my first project that I included a luminance image, M33. I image in Bortle 7 skies. I h...
Luminance channel issues in mono camera imaging, similar diagnostic approach.
Jan 7, 2026